diff --git a/mozilla/content/events/src/nsEventStateManager.cpp b/mozilla/content/events/src/nsEventStateManager.cpp
index 8d80c83b32c..65f0b8fdcd4 100644
--- a/mozilla/content/events/src/nsEventStateManager.cpp
+++ b/mozilla/content/events/src/nsEventStateManager.cpp
@@ -428,7 +428,7 @@ nsEventStateManager::ShiftFocus()
     if (nsnull == mDocument) {
       nsCOMPtr<nsIPresShell> presShell;
       mPresContext->GetShell(getter_AddRefs(presShell));
-      if (nsnull != presShell) {
+      if (presShell) {
         presShell->GetDocument(&mDocument);
         if (nsnull == mDocument) {
           return;
diff --git a/mozilla/content/html/content/src/nsHTMLBodyElement.cpp b/mozilla/content/html/content/src/nsHTMLBodyElement.cpp
index 540b5b99c67..8699139d98f 100644
--- a/mozilla/content/html/content/src/nsHTMLBodyElement.cpp
+++ b/mozilla/content/html/content/src/nsHTMLBodyElement.cpp
@@ -653,10 +653,10 @@ MapAttributesInto(nsIHTMLAttributes* aAttributes,
 
     nsCOMPtr<nsIPresShell> presShell;
     aPresContext->GetShell(getter_AddRefs(presShell));
-    if (nsnull != presShell) {
+    if (presShell) {
       nsCOMPtr<nsIDocument> doc;
       presShell->GetDocument(getter_AddRefs(doc));
-      if (nsnull != doc) {
+      if (doc) {
         nsIHTMLContentContainer*  htmlContainer;
         if (NS_OK == doc->QueryInterface(kIHTMLContentContainerIID,
                                          (void**)&htmlContainer)) {
diff --git a/mozilla/content/html/content/src/nsHTMLFontElement.cpp b/mozilla/content/html/content/src/nsHTMLFontElement.cpp
index c29a9fc1034..8cbea837c54 100644
--- a/mozilla/content/html/content/src/nsHTMLFontElement.cpp
+++ b/mozilla/content/html/content/src/nsHTMLFontElement.cpp
@@ -211,7 +211,7 @@ MapAttributesInto(nsIHTMLAttributes* aAttributes,
 
       nsCOMPtr<nsIDeviceContext> dc;
       aPresContext->GetDeviceContext(getter_AddRefs(dc));
-      if (nsnull != dc) {
+      if (dc) {
         nsAutoString  familyList;
 
         value.GetStringValue(familyList);
diff --git a/mozilla/content/html/content/src/nsHTMLFormElement.cpp b/mozilla/content/html/content/src/nsHTMLFormElement.cpp
index de1ed08139e..1766b2d131d 100644
--- a/mozilla/content/html/content/src/nsHTMLFormElement.cpp
+++ b/mozilla/content/html/content/src/nsHTMLFormElement.cpp
@@ -284,7 +284,7 @@ nsHTMLFormElement::Submit()
         if ((NS_OK == result) && formMan) {
           nsCOMPtr<nsIPresContext> context;
           shell->GetPresContext(getter_AddRefs(context));
-          if (nsnull != context) {
+          if (context) {
             // XXX We're currently passing in null for the frame.
             // It works for now, but might not always
             // be correct. In the future, we might not need the 
diff --git a/mozilla/content/html/document/src/nsHTMLContentSink.cpp b/mozilla/content/html/document/src/nsHTMLContentSink.cpp
index 1bbec34bd6c..b830ea4fc97 100644
--- a/mozilla/content/html/document/src/nsHTMLContentSink.cpp
+++ b/mozilla/content/html/document/src/nsHTMLContentSink.cpp
@@ -1460,10 +1460,10 @@ HTMLContentSink::DidBuildModel(PRInt32 aQualityLevel)
   PRInt32 i, ns = mDocument->GetNumberOfShells();
   for (i = 0; i < ns; i++) {
     nsCOMPtr<nsIPresShell> shell(mDocument->GetShellAt(i));
-    if (nsnull != shell) {
+    if (shell) {
       nsCOMPtr<nsIViewManager> vm;
       nsresult rv = shell->GetViewManager(getter_AddRefs(vm));
-      if(NS_SUCCEEDED(rv) && (nsnull != vm)) {
+      if(NS_SUCCEEDED(rv) && vm) {
         vm->SetQuality(nsContentQuality(aQualityLevel));
       }
     }
@@ -1972,7 +1972,7 @@ HTMLContentSink::StartLayout()
   PRInt32 i, ns = mDocument->GetNumberOfShells();
   for (i = 0; i < ns; i++) {
     nsCOMPtr<nsIPresShell> shell(mDocument->GetShellAt(i));
-    if (nsnull != shell) {
+    if (shell) {
       // Make shell an observer for next time
       shell->BeginObservingDocument();
 
@@ -1986,7 +1986,7 @@ HTMLContentSink::StartLayout()
       // Now trigger a refresh
       nsCOMPtr<nsIViewManager> vm;
       shell->GetViewManager(getter_AddRefs(vm));
-      if (nsnull != vm) {
+      if (vm) {
         vm->EnableRefresh();
       }
     }
@@ -2008,10 +2008,10 @@ HTMLContentSink::StartLayout()
     PRInt32 i, ns = mDocument->GetNumberOfShells();
     for (i = 0; i < ns; i++) {
       nsCOMPtr<nsIPresShell> shell(mDocument->GetShellAt(i));
-      if (nsnull != shell) {
+      if (shell) {
         nsCOMPtr<nsIViewManager> vm;
         shell->GetViewManager(getter_AddRefs(vm));
-        if (nsnull != vm) {
+        if (vm) {
           nsIView* rootView = nsnull;
           vm->GetRootView(rootView);
           if (nsnull != rootView) {
@@ -2039,13 +2039,13 @@ HTMLContentSink::ScrollToRef()
     PRInt32 i, ns = mDocument->GetNumberOfShells();
     for (i = 0; i < ns; i++) {
       nsCOMPtr<nsIPresShell> shell(mDocument->GetShellAt(i));
-      if (nsnull != shell) {
+      if (shell) {
         nsIFrame* frame;
         shell->GetPrimaryFrameFor(mRefContent, &frame);
         if (nsnull != frame) {
           nsCOMPtr<nsIViewManager> vm;
           shell->GetViewManager(getter_AddRefs(vm));
-          if (nsnull != vm) {
+          if (vm) {
             nsIView* viewportView = nsnull;
             vm->GetRootView(viewportView);
             if (nsnull != viewportView) {
diff --git a/mozilla/content/html/document/src/nsHTMLDocument.cpp b/mozilla/content/html/document/src/nsHTMLDocument.cpp
index 31f5f00efe2..c1ead9bc866 100644
--- a/mozilla/content/html/document/src/nsHTMLDocument.cpp
+++ b/mozilla/content/html/document/src/nsHTMLDocument.cpp
@@ -525,7 +525,7 @@ nsHTMLDocument::InsertStyleSheetAt(nsIStyleSheet* aSheet, PRInt32 aIndex, PRBool
       nsIPresShell* shell = (nsIPresShell*)mPresShells.ElementAt(index);
       nsCOMPtr<nsIStyleSet> set;
       shell->GetStyleSet(getter_AddRefs(set));
-      if (nsnull != set) {
+      if (set) {
         set->AddDocStyleSheet(aSheet, this);
       }
     }
diff --git a/mozilla/content/html/document/src/nsImageDocument.cpp b/mozilla/content/html/document/src/nsImageDocument.cpp
index 8422dba7312..d42c2e3d4b0 100644
--- a/mozilla/content/html/document/src/nsImageDocument.cpp
+++ b/mozilla/content/html/document/src/nsImageDocument.cpp
@@ -221,7 +221,7 @@ nsImageDocument::StartImageLoad(nsIURL* aURL, nsIStreamListener*& aListener)
   if (nsnull != shell) {
     nsCOMPtr<nsIPresContext> cx;
     shell->GetPresContext(getter_AddRefs(cx));
-    if (nsnull != cx) {
+    if (cx) {
       nsIImageGroup* group = nsnull;
       cx->GetImageGroup(&group);
       if (nsnull != group) {
@@ -327,7 +327,7 @@ nsImageDocument::StartLayout()
       // XXX It's unfortunate that this has to be here
       nsCOMPtr<nsIViewManager> vm;
       shell->GetViewManager(getter_AddRefs(vm));
-      if (nsnull != vm) {
+      if (vm) {
         vm->EnableRefresh();
       }
 
diff --git a/mozilla/content/html/style/src/nsCSSStyleRule.cpp b/mozilla/content/html/style/src/nsCSSStyleRule.cpp
index 32d9206d16d..12d291d2af6 100644
--- a/mozilla/content/html/style/src/nsCSSStyleRule.cpp
+++ b/mozilla/content/html/style/src/nsCSSStyleRule.cpp
@@ -1169,7 +1169,7 @@ void MapDeclarationInto(nsICSSDeclaration* aDeclaration,
         if (eCSSUnit_String == ourFont->mFamily.GetUnit()) {
           nsCOMPtr<nsIDeviceContext> dc;
           aPresContext->GetDeviceContext(getter_AddRefs(dc));
-          if (nsnull != dc) {
+          if (dc) {
             nsAutoString  familyList;
 
             ourFont->mFamily.GetStringValue(familyList);
diff --git a/mozilla/content/xml/document/src/nsXMLContentSink.cpp b/mozilla/content/xml/document/src/nsXMLContentSink.cpp
index cff7be3cfc3..70a1da0d56d 100644
--- a/mozilla/content/xml/document/src/nsXMLContentSink.cpp
+++ b/mozilla/content/xml/document/src/nsXMLContentSink.cpp
@@ -230,7 +230,7 @@ nsXMLContentSink::DidBuildModel(PRInt32 aQualityLevel)
   PRInt32 i, ns = mDocument->GetNumberOfShells();
   for (i = 0; i < ns; i++) {
     nsCOMPtr<nsIPresShell> shell(mDocument->GetShellAt(i));
-    if (nsnull != shell) {
+    if (shell) {
       nsCOMPtr<nsIViewManager> vm;
       shell->GetViewManager(getter_AddRefs(vm));
       if(vm) {
@@ -1323,7 +1323,7 @@ nsXMLContentSink::StartLayout()
       // Now trigger a refresh
       nsCOMPtr<nsIViewManager> vm;
       shell->GetViewManager(getter_AddRefs(vm));
-      if (nsnull != vm) {
+      if (vm) {
         vm->EnableRefresh();
       }
 
@@ -1356,7 +1356,7 @@ nsXMLContentSink::StartLayout()
       if (nsnull != shell) {
         nsCOMPtr<nsIViewManager>vm;
         shell->GetViewManager(getter_AddRefs(vm));
-        if (nsnull != vm) {
+        if (vm) {
           nsIView* rootView = nsnull;
           vm->GetRootView(rootView);
           if (nsnull != rootView) {
diff --git a/mozilla/content/xul/document/src/nsXULDocument.cpp b/mozilla/content/xul/document/src/nsXULDocument.cpp
index d87a59ccb51..2725d3227a0 100644
--- a/mozilla/content/xul/document/src/nsXULDocument.cpp
+++ b/mozilla/content/xul/document/src/nsXULDocument.cpp
@@ -1145,7 +1145,7 @@ XULDocumentImpl::AddStyleSheet(nsIStyleSheet* aSheet)
             nsIPresShell* shell = NS_STATIC_CAST(nsIPresShell*, mPresShells[index]);
             nsCOMPtr<nsIStyleSet> set;
             shell->GetStyleSet(getter_AddRefs(set));
-            if (nsnull != set) {
+            if (set) {
                 set->AddDocStyleSheet(aSheet, this);
             }
         }
@@ -1174,7 +1174,7 @@ XULDocumentImpl::SetStyleSheetDisabledState(nsIStyleSheet* aSheet,
             nsIPresShell* shell = (nsIPresShell*)mPresShells.ElementAt(index);
             nsCOMPtr<nsIStyleSet> set;
             shell->GetStyleSet(getter_AddRefs(set));
-            if (nsnull != set) {
+            if (set) {
                 if (aDisabled) {
                     set->RemoveDocStyleSheet(aSheet);
                 }
@@ -2150,7 +2150,7 @@ XULDocumentImpl::StartLayout(void)
         // Now trigger a refresh
         nsCOMPtr<nsIViewManager> vm;
         shell->GetViewManager(getter_AddRefs(vm));
-        if (nsnull != vm) {
+        if (vm) {
             vm->EnableRefresh();
         }
 
diff --git a/mozilla/layout/base/nsPresContext.cpp b/mozilla/layout/base/nsPresContext.cpp
index 3d9d54730b6..6466c966a86 100644
--- a/mozilla/layout/base/nsPresContext.cpp
+++ b/mozilla/layout/base/nsPresContext.cpp
@@ -242,8 +242,8 @@ nsPresContext::SetShell(nsIPresShell* aShell)
   if (nsnull != mShell) {
     nsCOMPtr<nsIDocument> doc;
     if (NS_SUCCEEDED(mShell->GetDocument(getter_AddRefs(doc)))) {
-      NS_ASSERTION(nsnull != doc, "expect document here");
-      if (nsnull != doc) {
+      NS_ASSERTION(doc, "expect document here");
+      if (doc) {
         doc->GetBaseURL(mBaseURL);
       }
     }
@@ -320,7 +320,7 @@ nsPresContext::ResolveStyleContextFor(nsIContent* aContent,
   nsCOMPtr<nsIStyleSet> set;
   nsresult rv = mShell->GetStyleSet(getter_AddRefs(set));
   if (NS_SUCCEEDED(rv)) {
-    if (nsnull != set) {
+    if (set) {
       result = set->ResolveStyleFor(this, aContent, aParentContext,
                                     aForceUnique);
       if (nsnull == result) {
@@ -348,7 +348,7 @@ nsPresContext::ResolvePseudoStyleContextFor(nsIContent* aParentContent,
   nsCOMPtr<nsIStyleSet> set;
   nsresult rv = mShell->GetStyleSet(getter_AddRefs(set));
   if (NS_SUCCEEDED(rv)) {
-    if (nsnull != set) {
+    if (set) {
       result = set->ResolvePseudoStyleFor(this, aParentContent, aPseudoTag,
                                           aParentContext, aForceUnique);
       if (nsnull == result) {
@@ -376,7 +376,7 @@ nsPresContext::ProbePseudoStyleContextFor(nsIContent* aParentContent,
   nsCOMPtr<nsIStyleSet> set;
   nsresult rv = mShell->GetStyleSet(getter_AddRefs(set));
   if (NS_SUCCEEDED(rv)) {
-    if (nsnull != set) {
+    if (set) {
       result = set->ProbePseudoStyleFor(this, aParentContent, aPseudoTag,
                                         aParentContext, aForceUnique);
     }
diff --git a/mozilla/layout/base/nsPresShell.cpp b/mozilla/layout/base/nsPresShell.cpp
index 93d4ef1b8d5..1e50e9f25c0 100644
--- a/mozilla/layout/base/nsPresShell.cpp
+++ b/mozilla/layout/base/nsPresShell.cpp
@@ -1160,7 +1160,7 @@ PresShell::CreateRenderingContext(nsIFrame *aFrame,
 
   nsIRenderingContext* result = nsnull;
   rv = mPresContext->GetDeviceContext(getter_AddRefs(dx));
-  if (NS_SUCCEEDED(rv) && (nsnull != dx)) {
+  if (NS_SUCCEEDED(rv) && dx) {
     if (nsnull != view) {
       rv = dx->CreateRenderingContext(view, result);
     }
diff --git a/mozilla/layout/base/src/nsPresContext.cpp b/mozilla/layout/base/src/nsPresContext.cpp
index 3d9d54730b6..6466c966a86 100644
--- a/mozilla/layout/base/src/nsPresContext.cpp
+++ b/mozilla/layout/base/src/nsPresContext.cpp
@@ -242,8 +242,8 @@ nsPresContext::SetShell(nsIPresShell* aShell)
   if (nsnull != mShell) {
     nsCOMPtr<nsIDocument> doc;
     if (NS_SUCCEEDED(mShell->GetDocument(getter_AddRefs(doc)))) {
-      NS_ASSERTION(nsnull != doc, "expect document here");
-      if (nsnull != doc) {
+      NS_ASSERTION(doc, "expect document here");
+      if (doc) {
         doc->GetBaseURL(mBaseURL);
       }
     }
@@ -320,7 +320,7 @@ nsPresContext::ResolveStyleContextFor(nsIContent* aContent,
   nsCOMPtr<nsIStyleSet> set;
   nsresult rv = mShell->GetStyleSet(getter_AddRefs(set));
   if (NS_SUCCEEDED(rv)) {
-    if (nsnull != set) {
+    if (set) {
       result = set->ResolveStyleFor(this, aContent, aParentContext,
                                     aForceUnique);
       if (nsnull == result) {
@@ -348,7 +348,7 @@ nsPresContext::ResolvePseudoStyleContextFor(nsIContent* aParentContent,
   nsCOMPtr<nsIStyleSet> set;
   nsresult rv = mShell->GetStyleSet(getter_AddRefs(set));
   if (NS_SUCCEEDED(rv)) {
-    if (nsnull != set) {
+    if (set) {
       result = set->ResolvePseudoStyleFor(this, aParentContent, aPseudoTag,
                                           aParentContext, aForceUnique);
       if (nsnull == result) {
@@ -376,7 +376,7 @@ nsPresContext::ProbePseudoStyleContextFor(nsIContent* aParentContent,
   nsCOMPtr<nsIStyleSet> set;
   nsresult rv = mShell->GetStyleSet(getter_AddRefs(set));
   if (NS_SUCCEEDED(rv)) {
-    if (nsnull != set) {
+    if (set) {
       result = set->ProbePseudoStyleFor(this, aParentContent, aPseudoTag,
                                         aParentContext, aForceUnique);
     }
diff --git a/mozilla/layout/base/src/nsRangeList.cpp b/mozilla/layout/base/src/nsRangeList.cpp
index 39d79922c16..ea5a22eacda 100644
--- a/mozilla/layout/base/src/nsRangeList.cpp
+++ b/mozilla/layout/base/src/nsRangeList.cpp
@@ -753,7 +753,7 @@ nsRangeList::TakeFocus(nsIFocusTracker *aTracker, nsIFrame *aFrame, PRInt32 aOff
           nsCOMPtr<nsIContent>oldContent;
           if (NS_SUCCEEDED(frame->GetContent(getter_AddRefs(oldContent))) && oldContent){
             nsCOMPtr<nsIDOMNode> oldDomNode(oldContent);
-            if ((nsnull != oldDomNode) && (oldDomNode == GetFocusNode())) {
+            if (oldDomNode && (oldDomNode == GetFocusNode())) {
               nsCOMPtr<nsIContent> anchorContent;
               if (NS_SUCCEEDED(anchor->GetContent(getter_AddRefs(anchorContent))) && anchorContent){
                 nsCOMPtr<nsIDOMNode>anchorDomNode(anchorContent);
diff --git a/mozilla/layout/events/src/nsEventStateManager.cpp b/mozilla/layout/events/src/nsEventStateManager.cpp
index 8d80c83b32c..65f0b8fdcd4 100644
--- a/mozilla/layout/events/src/nsEventStateManager.cpp
+++ b/mozilla/layout/events/src/nsEventStateManager.cpp
@@ -428,7 +428,7 @@ nsEventStateManager::ShiftFocus()
     if (nsnull == mDocument) {
       nsCOMPtr<nsIPresShell> presShell;
       mPresContext->GetShell(getter_AddRefs(presShell));
-      if (nsnull != presShell) {
+      if (presShell) {
         presShell->GetDocument(&mDocument);
         if (nsnull == mDocument) {
           return;
diff --git a/mozilla/layout/forms/nsFormControlFrame.cpp b/mozilla/layout/forms/nsFormControlFrame.cpp
index 46c7be5ea0c..77aaa107484 100644
--- a/mozilla/layout/forms/nsFormControlFrame.cpp
+++ b/mozilla/layout/forms/nsFormControlFrame.cpp
@@ -226,7 +226,7 @@ nsFormControlFrame::Reflow(nsIPresContext&      aPresContext,
   PRBool requiresWidget = PR_TRUE;
  
     // Checkto see if the device context supports widgets at all
-  if (nsnull != dx) { 
+  if (dx) { 
     dx->SupportsNativeWidgets(requiresWidget);
   }
 
diff --git a/mozilla/layout/forms/nsListControlFrame.cpp b/mozilla/layout/forms/nsListControlFrame.cpp
index d6fabda2f7c..4a5159c4b73 100644
--- a/mozilla/layout/forms/nsListControlFrame.cpp
+++ b/mozilla/layout/forms/nsListControlFrame.cpp
@@ -841,7 +841,7 @@ nsListControlFrame::GetScrollBarDimensions(nsIPresContext& aPresContext,
   float   scale;
   nsCOMPtr<nsIDeviceContext> dx;
   aPresContext.GetDeviceContext(getter_AddRefs(dx));
-  if (nsnull != dx) { 
+  if (dx) { 
     float sbWidth;
     float sbHeight;
     dx->GetCanonicalPixelScale(scale);
diff --git a/mozilla/layout/forms/nsTextControlFrame.cpp b/mozilla/layout/forms/nsTextControlFrame.cpp
index c9f9f48f57a..7467b68a8dd 100644
--- a/mozilla/layout/forms/nsTextControlFrame.cpp
+++ b/mozilla/layout/forms/nsTextControlFrame.cpp
@@ -273,7 +273,7 @@ nsTextControlFrame::GetDesiredSize(nsIPresContext* aPresContext,
     aPresContext->GetPixelsToTwips(&p2t);
     nsCOMPtr<nsIDeviceContext> dx;
     aPresContext->GetDeviceContext(getter_AddRefs(dx));
-    if (nsnull != dx) { 
+    if (dx) { 
       float sbWidth;
       float sbHeight;
       dx->GetCanonicalPixelScale(scale);
diff --git a/mozilla/layout/generic/nsBulletFrame.cpp b/mozilla/layout/generic/nsBulletFrame.cpp
index 68b5e12684d..7d9dea2ae88 100644
--- a/mozilla/layout/generic/nsBulletFrame.cpp
+++ b/mozilla/layout/generic/nsBulletFrame.cpp
@@ -315,7 +315,7 @@ UpdateBulletCB(nsIPresContext& aPresContext, nsIFrame* aFrame, PRIntn aStatus)
     // frame.
     nsCOMPtr<nsIPresShell> shell;
     rv = aPresContext.GetShell(getter_AddRefs(shell));
-    if (NS_SUCCEEDED(rv) && (nsnull != shell)) {
+    if (NS_SUCCEEDED(rv) && shell) {
       nsIReflowCommand* cmd;
       rv = NS_NewHTMLReflowCommand(&cmd, aFrame,
                                    nsIReflowCommand::ContentChanged);
diff --git a/mozilla/layout/generic/nsFrame.cpp b/mozilla/layout/generic/nsFrame.cpp
index 002861ff517..049a400328f 100644
--- a/mozilla/layout/generic/nsFrame.cpp
+++ b/mozilla/layout/generic/nsFrame.cpp
@@ -363,7 +363,7 @@ nsFrame::DeleteFrame(nsIPresContext& aPresContext)
   if (mState & NS_FRAME_EXTERNAL_REFERENCE) {
     nsCOMPtr<nsIPresShell> shell;
     nsresult rv = aPresContext.GetShell(getter_AddRefs(shell));
-    if (NS_SUCCEEDED(rv) && (nsnull != shell)) {
+    if (NS_SUCCEEDED(rv) && shell) {
       shell->ClearFrameRefs(this);
     }
   }
@@ -594,10 +594,10 @@ nsFrame::DisplaySelection(nsIPresContext& aPresContext, PRBool isOkToTurnOn)
 
   nsCOMPtr<nsIPresShell> shell;
   nsresult rv = aPresContext.GetShell(getter_AddRefs(shell));
-  if (NS_SUCCEEDED(rv) && (nsnull != shell)) {
+  if (NS_SUCCEEDED(rv) && shell) {
     nsCOMPtr<nsIDocument> doc;
     rv = shell->GetDocument(getter_AddRefs(doc));
-    if (NS_SUCCEEDED(rv) && (nsnull != doc)) {
+    if (NS_SUCCEEDED(rv) && doc) {
       result = doc->GetDisplaySelection();
       if (isOkToTurnOn && !result) {
         doc->SetDisplaySelection(PR_TRUE);
@@ -705,7 +705,7 @@ nsFrame::HandlePress(nsIPresContext& aPresContext,
   mDidDrag        = PR_FALSE;
   nsCOMPtr<nsIPresShell> shell;
   nsresult rv = aPresContext.GetShell(getter_AddRefs(shell));
-  if (NS_SUCCEEDED(rv) && (nsnull != shell)) {
+  if (NS_SUCCEEDED(rv) && shell) {
     nsCOMPtr<nsIRenderingContext> acx;      
     rv = shell->CreateRenderingContext(this, getter_AddRefs(acx));
     if (NS_SUCCEEDED(rv)){
@@ -923,7 +923,7 @@ NS_IMETHODIMP nsFrame::HandleDrag(nsIPresContext& aPresContext,
   mDidDrag        = PR_FALSE;
   nsCOMPtr<nsIPresShell> shell;
   nsresult rv = aPresContext.GetShell(getter_AddRefs(shell));
-  if (NS_SUCCEEDED(rv) && (nsnull != shell)) {
+  if (NS_SUCCEEDED(rv) && shell) {
     nsCOMPtr<nsIRenderingContext> acx;      
     rv = shell->CreateRenderingContext(this, getter_AddRefs(acx));
     if (NS_SUCCEEDED(rv)) {
@@ -1348,7 +1348,7 @@ nsFrame::ContentChanged(nsIPresContext* aPresContext,
 {
   nsCOMPtr<nsIPresShell> shell;
   nsresult rv = aPresContext->GetShell(getter_AddRefs(shell));
-  if (NS_SUCCEEDED(rv) && (nsnull != shell)) {
+  if (NS_SUCCEEDED(rv) && shell) {
     nsIReflowCommand* reflowCmd;
     rv = NS_NewHTMLReflowCommand(&reflowCmd, this,
                                  nsIReflowCommand::ContentChanged);
diff --git a/mozilla/layout/generic/nsHTMLReflowCommand.cpp b/mozilla/layout/generic/nsHTMLReflowCommand.cpp
index c41c559501f..96d53c00cf9 100644
--- a/mozilla/layout/generic/nsHTMLReflowCommand.cpp
+++ b/mozilla/layout/generic/nsHTMLReflowCommand.cpp
@@ -145,7 +145,7 @@ NS_IMETHODIMP nsHTMLReflowCommand::Dispatch(nsIPresContext&      aPresContext,
 #ifdef NS_DEBUG
   nsCOMPtr<nsIPresShell> shell;
   aPresContext.GetShell(getter_AddRefs(shell));
-  if (nsnull != shell) {
+  if (shell) {
     nsIFrame* rootFrame;
     shell->GetRootFrame(&rootFrame);
     NS_ASSERTION(rootFrame == root, "bad root frame");
diff --git a/mozilla/layout/generic/nsInlineFrame.cpp b/mozilla/layout/generic/nsInlineFrame.cpp
index 1aeb0f59c38..db41fb8e2d2 100644
--- a/mozilla/layout/generic/nsInlineFrame.cpp
+++ b/mozilla/layout/generic/nsInlineFrame.cpp
@@ -451,7 +451,7 @@ nsInlineFrame::SetInitialChildList(nsIPresContext& aPresContext,
   }
   nsCOMPtr<nsIPresShell> shell;
   nsresult rv = aPresContext.GetShell(getter_AddRefs(shell));
-  if (NS_SUCCEEDED(rv) && (nsnull != shell)) {
+  if (NS_SUCCEEDED(rv) && shell) {
     rv = AppendFrames(aPresContext, *shell, aFrameList, PR_FALSE);
   }
   return rv;
diff --git a/mozilla/layout/generic/nsLeafFrame.cpp b/mozilla/layout/generic/nsLeafFrame.cpp
index 79c7803a3bb..ba0f3c79adc 100644
--- a/mozilla/layout/generic/nsLeafFrame.cpp
+++ b/mozilla/layout/generic/nsLeafFrame.cpp
@@ -115,7 +115,7 @@ nsLeafFrame::ContentChanged(nsIPresContext* aPresContext,
   if (NS_SUCCEEDED(rv)) {
     nsCOMPtr<nsIPresShell> shell;
     rv = aPresContext->GetShell(getter_AddRefs(shell));
-    if (NS_SUCCEEDED(rv) && (nsnull != shell)) {
+    if (NS_SUCCEEDED(rv) && shell) {
       shell->AppendReflowCommand(cmd);
     }
     NS_RELEASE(cmd);
diff --git a/mozilla/layout/generic/nsTextFrame.cpp b/mozilla/layout/generic/nsTextFrame.cpp
index 208a38bae5b..9ee3a71cbd6 100644
--- a/mozilla/layout/generic/nsTextFrame.cpp
+++ b/mozilla/layout/generic/nsTextFrame.cpp
@@ -512,7 +512,7 @@ TextFrame::ContentChanged(nsIPresContext* aPresContext,
   if (NS_SUCCEEDED(rv)) {
     nsCOMPtr<nsIPresShell> shell;
     rv = aPresContext->GetShell(getter_AddRefs(shell));
-    if (NS_SUCCEEDED(rv) && (nsnull != shell)) {
+    if (NS_SUCCEEDED(rv) && shell) {
       shell->AppendReflowCommand(cmd);
       NS_RELEASE(cmd);
     }
diff --git a/mozilla/layout/html/base/src/nsBulletFrame.cpp b/mozilla/layout/html/base/src/nsBulletFrame.cpp
index 68b5e12684d..7d9dea2ae88 100644
--- a/mozilla/layout/html/base/src/nsBulletFrame.cpp
+++ b/mozilla/layout/html/base/src/nsBulletFrame.cpp
@@ -315,7 +315,7 @@ UpdateBulletCB(nsIPresContext& aPresContext, nsIFrame* aFrame, PRIntn aStatus)
     // frame.
     nsCOMPtr<nsIPresShell> shell;
     rv = aPresContext.GetShell(getter_AddRefs(shell));
-    if (NS_SUCCEEDED(rv) && (nsnull != shell)) {
+    if (NS_SUCCEEDED(rv) && shell) {
       nsIReflowCommand* cmd;
       rv = NS_NewHTMLReflowCommand(&cmd, aFrame,
                                    nsIReflowCommand::ContentChanged);
diff --git a/mozilla/layout/html/base/src/nsFrame.cpp b/mozilla/layout/html/base/src/nsFrame.cpp
index 002861ff517..049a400328f 100644
--- a/mozilla/layout/html/base/src/nsFrame.cpp
+++ b/mozilla/layout/html/base/src/nsFrame.cpp
@@ -363,7 +363,7 @@ nsFrame::DeleteFrame(nsIPresContext& aPresContext)
   if (mState & NS_FRAME_EXTERNAL_REFERENCE) {
     nsCOMPtr<nsIPresShell> shell;
     nsresult rv = aPresContext.GetShell(getter_AddRefs(shell));
-    if (NS_SUCCEEDED(rv) && (nsnull != shell)) {
+    if (NS_SUCCEEDED(rv) && shell) {
       shell->ClearFrameRefs(this);
     }
   }
@@ -594,10 +594,10 @@ nsFrame::DisplaySelection(nsIPresContext& aPresContext, PRBool isOkToTurnOn)
 
   nsCOMPtr<nsIPresShell> shell;
   nsresult rv = aPresContext.GetShell(getter_AddRefs(shell));
-  if (NS_SUCCEEDED(rv) && (nsnull != shell)) {
+  if (NS_SUCCEEDED(rv) && shell) {
     nsCOMPtr<nsIDocument> doc;
     rv = shell->GetDocument(getter_AddRefs(doc));
-    if (NS_SUCCEEDED(rv) && (nsnull != doc)) {
+    if (NS_SUCCEEDED(rv) && doc) {
       result = doc->GetDisplaySelection();
       if (isOkToTurnOn && !result) {
         doc->SetDisplaySelection(PR_TRUE);
@@ -705,7 +705,7 @@ nsFrame::HandlePress(nsIPresContext& aPresContext,
   mDidDrag        = PR_FALSE;
   nsCOMPtr<nsIPresShell> shell;
   nsresult rv = aPresContext.GetShell(getter_AddRefs(shell));
-  if (NS_SUCCEEDED(rv) && (nsnull != shell)) {
+  if (NS_SUCCEEDED(rv) && shell) {
     nsCOMPtr<nsIRenderingContext> acx;      
     rv = shell->CreateRenderingContext(this, getter_AddRefs(acx));
     if (NS_SUCCEEDED(rv)){
@@ -923,7 +923,7 @@ NS_IMETHODIMP nsFrame::HandleDrag(nsIPresContext& aPresContext,
   mDidDrag        = PR_FALSE;
   nsCOMPtr<nsIPresShell> shell;
   nsresult rv = aPresContext.GetShell(getter_AddRefs(shell));
-  if (NS_SUCCEEDED(rv) && (nsnull != shell)) {
+  if (NS_SUCCEEDED(rv) && shell) {
     nsCOMPtr<nsIRenderingContext> acx;      
     rv = shell->CreateRenderingContext(this, getter_AddRefs(acx));
     if (NS_SUCCEEDED(rv)) {
@@ -1348,7 +1348,7 @@ nsFrame::ContentChanged(nsIPresContext* aPresContext,
 {
   nsCOMPtr<nsIPresShell> shell;
   nsresult rv = aPresContext->GetShell(getter_AddRefs(shell));
-  if (NS_SUCCEEDED(rv) && (nsnull != shell)) {
+  if (NS_SUCCEEDED(rv) && shell) {
     nsIReflowCommand* reflowCmd;
     rv = NS_NewHTMLReflowCommand(&reflowCmd, this,
                                  nsIReflowCommand::ContentChanged);
diff --git a/mozilla/layout/html/base/src/nsHTMLReflowCommand.cpp b/mozilla/layout/html/base/src/nsHTMLReflowCommand.cpp
index c41c559501f..96d53c00cf9 100644
--- a/mozilla/layout/html/base/src/nsHTMLReflowCommand.cpp
+++ b/mozilla/layout/html/base/src/nsHTMLReflowCommand.cpp
@@ -145,7 +145,7 @@ NS_IMETHODIMP nsHTMLReflowCommand::Dispatch(nsIPresContext&      aPresContext,
 #ifdef NS_DEBUG
   nsCOMPtr<nsIPresShell> shell;
   aPresContext.GetShell(getter_AddRefs(shell));
-  if (nsnull != shell) {
+  if (shell) {
     nsIFrame* rootFrame;
     shell->GetRootFrame(&rootFrame);
     NS_ASSERTION(rootFrame == root, "bad root frame");
diff --git a/mozilla/layout/html/base/src/nsInlineFrame.cpp b/mozilla/layout/html/base/src/nsInlineFrame.cpp
index 1aeb0f59c38..db41fb8e2d2 100644
--- a/mozilla/layout/html/base/src/nsInlineFrame.cpp
+++ b/mozilla/layout/html/base/src/nsInlineFrame.cpp
@@ -451,7 +451,7 @@ nsInlineFrame::SetInitialChildList(nsIPresContext& aPresContext,
   }
   nsCOMPtr<nsIPresShell> shell;
   nsresult rv = aPresContext.GetShell(getter_AddRefs(shell));
-  if (NS_SUCCEEDED(rv) && (nsnull != shell)) {
+  if (NS_SUCCEEDED(rv) && shell) {
     rv = AppendFrames(aPresContext, *shell, aFrameList, PR_FALSE);
   }
   return rv;
diff --git a/mozilla/layout/html/base/src/nsLeafFrame.cpp b/mozilla/layout/html/base/src/nsLeafFrame.cpp
index 79c7803a3bb..ba0f3c79adc 100644
--- a/mozilla/layout/html/base/src/nsLeafFrame.cpp
+++ b/mozilla/layout/html/base/src/nsLeafFrame.cpp
@@ -115,7 +115,7 @@ nsLeafFrame::ContentChanged(nsIPresContext* aPresContext,
   if (NS_SUCCEEDED(rv)) {
     nsCOMPtr<nsIPresShell> shell;
     rv = aPresContext->GetShell(getter_AddRefs(shell));
-    if (NS_SUCCEEDED(rv) && (nsnull != shell)) {
+    if (NS_SUCCEEDED(rv) && shell) {
       shell->AppendReflowCommand(cmd);
     }
     NS_RELEASE(cmd);
diff --git a/mozilla/layout/html/base/src/nsPresShell.cpp b/mozilla/layout/html/base/src/nsPresShell.cpp
index 93d4ef1b8d5..1e50e9f25c0 100644
--- a/mozilla/layout/html/base/src/nsPresShell.cpp
+++ b/mozilla/layout/html/base/src/nsPresShell.cpp
@@ -1160,7 +1160,7 @@ PresShell::CreateRenderingContext(nsIFrame *aFrame,
 
   nsIRenderingContext* result = nsnull;
   rv = mPresContext->GetDeviceContext(getter_AddRefs(dx));
-  if (NS_SUCCEEDED(rv) && (nsnull != dx)) {
+  if (NS_SUCCEEDED(rv) && dx) {
     if (nsnull != view) {
       rv = dx->CreateRenderingContext(view, result);
     }
diff --git a/mozilla/layout/html/base/src/nsTextFrame.cpp b/mozilla/layout/html/base/src/nsTextFrame.cpp
index 208a38bae5b..9ee3a71cbd6 100644
--- a/mozilla/layout/html/base/src/nsTextFrame.cpp
+++ b/mozilla/layout/html/base/src/nsTextFrame.cpp
@@ -512,7 +512,7 @@ TextFrame::ContentChanged(nsIPresContext* aPresContext,
   if (NS_SUCCEEDED(rv)) {
     nsCOMPtr<nsIPresShell> shell;
     rv = aPresContext->GetShell(getter_AddRefs(shell));
-    if (NS_SUCCEEDED(rv) && (nsnull != shell)) {
+    if (NS_SUCCEEDED(rv) && shell) {
       shell->AppendReflowCommand(cmd);
       NS_RELEASE(cmd);
     }
diff --git a/mozilla/layout/html/content/src/nsHTMLBodyElement.cpp b/mozilla/layout/html/content/src/nsHTMLBodyElement.cpp
index 540b5b99c67..8699139d98f 100644
--- a/mozilla/layout/html/content/src/nsHTMLBodyElement.cpp
+++ b/mozilla/layout/html/content/src/nsHTMLBodyElement.cpp
@@ -653,10 +653,10 @@ MapAttributesInto(nsIHTMLAttributes* aAttributes,
 
     nsCOMPtr<nsIPresShell> presShell;
     aPresContext->GetShell(getter_AddRefs(presShell));
-    if (nsnull != presShell) {
+    if (presShell) {
       nsCOMPtr<nsIDocument> doc;
       presShell->GetDocument(getter_AddRefs(doc));
-      if (nsnull != doc) {
+      if (doc) {
         nsIHTMLContentContainer*  htmlContainer;
         if (NS_OK == doc->QueryInterface(kIHTMLContentContainerIID,
                                          (void**)&htmlContainer)) {
diff --git a/mozilla/layout/html/content/src/nsHTMLFontElement.cpp b/mozilla/layout/html/content/src/nsHTMLFontElement.cpp
index c29a9fc1034..8cbea837c54 100644
--- a/mozilla/layout/html/content/src/nsHTMLFontElement.cpp
+++ b/mozilla/layout/html/content/src/nsHTMLFontElement.cpp
@@ -211,7 +211,7 @@ MapAttributesInto(nsIHTMLAttributes* aAttributes,
 
       nsCOMPtr<nsIDeviceContext> dc;
       aPresContext->GetDeviceContext(getter_AddRefs(dc));
-      if (nsnull != dc) {
+      if (dc) {
         nsAutoString  familyList;
 
         value.GetStringValue(familyList);
diff --git a/mozilla/layout/html/content/src/nsHTMLFormElement.cpp b/mozilla/layout/html/content/src/nsHTMLFormElement.cpp
index de1ed08139e..1766b2d131d 100644
--- a/mozilla/layout/html/content/src/nsHTMLFormElement.cpp
+++ b/mozilla/layout/html/content/src/nsHTMLFormElement.cpp
@@ -284,7 +284,7 @@ nsHTMLFormElement::Submit()
         if ((NS_OK == result) && formMan) {
           nsCOMPtr<nsIPresContext> context;
           shell->GetPresContext(getter_AddRefs(context));
-          if (nsnull != context) {
+          if (context) {
             // XXX We're currently passing in null for the frame.
             // It works for now, but might not always
             // be correct. In the future, we might not need the 
diff --git a/mozilla/layout/html/document/src/nsHTMLContentSink.cpp b/mozilla/layout/html/document/src/nsHTMLContentSink.cpp
index 1bbec34bd6c..b830ea4fc97 100644
--- a/mozilla/layout/html/document/src/nsHTMLContentSink.cpp
+++ b/mozilla/layout/html/document/src/nsHTMLContentSink.cpp
@@ -1460,10 +1460,10 @@ HTMLContentSink::DidBuildModel(PRInt32 aQualityLevel)
   PRInt32 i, ns = mDocument->GetNumberOfShells();
   for (i = 0; i < ns; i++) {
     nsCOMPtr<nsIPresShell> shell(mDocument->GetShellAt(i));
-    if (nsnull != shell) {
+    if (shell) {
       nsCOMPtr<nsIViewManager> vm;
       nsresult rv = shell->GetViewManager(getter_AddRefs(vm));
-      if(NS_SUCCEEDED(rv) && (nsnull != vm)) {
+      if(NS_SUCCEEDED(rv) && vm) {
         vm->SetQuality(nsContentQuality(aQualityLevel));
       }
     }
@@ -1972,7 +1972,7 @@ HTMLContentSink::StartLayout()
   PRInt32 i, ns = mDocument->GetNumberOfShells();
   for (i = 0; i < ns; i++) {
     nsCOMPtr<nsIPresShell> shell(mDocument->GetShellAt(i));
-    if (nsnull != shell) {
+    if (shell) {
       // Make shell an observer for next time
       shell->BeginObservingDocument();
 
@@ -1986,7 +1986,7 @@ HTMLContentSink::StartLayout()
       // Now trigger a refresh
       nsCOMPtr<nsIViewManager> vm;
       shell->GetViewManager(getter_AddRefs(vm));
-      if (nsnull != vm) {
+      if (vm) {
         vm->EnableRefresh();
       }
     }
@@ -2008,10 +2008,10 @@ HTMLContentSink::StartLayout()
     PRInt32 i, ns = mDocument->GetNumberOfShells();
     for (i = 0; i < ns; i++) {
       nsCOMPtr<nsIPresShell> shell(mDocument->GetShellAt(i));
-      if (nsnull != shell) {
+      if (shell) {
         nsCOMPtr<nsIViewManager> vm;
         shell->GetViewManager(getter_AddRefs(vm));
-        if (nsnull != vm) {
+        if (vm) {
           nsIView* rootView = nsnull;
           vm->GetRootView(rootView);
           if (nsnull != rootView) {
@@ -2039,13 +2039,13 @@ HTMLContentSink::ScrollToRef()
     PRInt32 i, ns = mDocument->GetNumberOfShells();
     for (i = 0; i < ns; i++) {
       nsCOMPtr<nsIPresShell> shell(mDocument->GetShellAt(i));
-      if (nsnull != shell) {
+      if (shell) {
         nsIFrame* frame;
         shell->GetPrimaryFrameFor(mRefContent, &frame);
         if (nsnull != frame) {
           nsCOMPtr<nsIViewManager> vm;
           shell->GetViewManager(getter_AddRefs(vm));
-          if (nsnull != vm) {
+          if (vm) {
             nsIView* viewportView = nsnull;
             vm->GetRootView(viewportView);
             if (nsnull != viewportView) {
diff --git a/mozilla/layout/html/document/src/nsHTMLDocument.cpp b/mozilla/layout/html/document/src/nsHTMLDocument.cpp
index 31f5f00efe2..c1ead9bc866 100644
--- a/mozilla/layout/html/document/src/nsHTMLDocument.cpp
+++ b/mozilla/layout/html/document/src/nsHTMLDocument.cpp
@@ -525,7 +525,7 @@ nsHTMLDocument::InsertStyleSheetAt(nsIStyleSheet* aSheet, PRInt32 aIndex, PRBool
       nsIPresShell* shell = (nsIPresShell*)mPresShells.ElementAt(index);
       nsCOMPtr<nsIStyleSet> set;
       shell->GetStyleSet(getter_AddRefs(set));
-      if (nsnull != set) {
+      if (set) {
         set->AddDocStyleSheet(aSheet, this);
       }
     }
diff --git a/mozilla/layout/html/document/src/nsImageDocument.cpp b/mozilla/layout/html/document/src/nsImageDocument.cpp
index 8422dba7312..d42c2e3d4b0 100644
--- a/mozilla/layout/html/document/src/nsImageDocument.cpp
+++ b/mozilla/layout/html/document/src/nsImageDocument.cpp
@@ -221,7 +221,7 @@ nsImageDocument::StartImageLoad(nsIURL* aURL, nsIStreamListener*& aListener)
   if (nsnull != shell) {
     nsCOMPtr<nsIPresContext> cx;
     shell->GetPresContext(getter_AddRefs(cx));
-    if (nsnull != cx) {
+    if (cx) {
       nsIImageGroup* group = nsnull;
       cx->GetImageGroup(&group);
       if (nsnull != group) {
@@ -327,7 +327,7 @@ nsImageDocument::StartLayout()
       // XXX It's unfortunate that this has to be here
       nsCOMPtr<nsIViewManager> vm;
       shell->GetViewManager(getter_AddRefs(vm));
-      if (nsnull != vm) {
+      if (vm) {
         vm->EnableRefresh();
       }
 
diff --git a/mozilla/layout/html/forms/src/nsFormControlFrame.cpp b/mozilla/layout/html/forms/src/nsFormControlFrame.cpp
index 46c7be5ea0c..77aaa107484 100644
--- a/mozilla/layout/html/forms/src/nsFormControlFrame.cpp
+++ b/mozilla/layout/html/forms/src/nsFormControlFrame.cpp
@@ -226,7 +226,7 @@ nsFormControlFrame::Reflow(nsIPresContext&      aPresContext,
   PRBool requiresWidget = PR_TRUE;
  
     // Checkto see if the device context supports widgets at all
-  if (nsnull != dx) { 
+  if (dx) { 
     dx->SupportsNativeWidgets(requiresWidget);
   }
 
diff --git a/mozilla/layout/html/forms/src/nsListControlFrame.cpp b/mozilla/layout/html/forms/src/nsListControlFrame.cpp
index d6fabda2f7c..4a5159c4b73 100644
--- a/mozilla/layout/html/forms/src/nsListControlFrame.cpp
+++ b/mozilla/layout/html/forms/src/nsListControlFrame.cpp
@@ -841,7 +841,7 @@ nsListControlFrame::GetScrollBarDimensions(nsIPresContext& aPresContext,
   float   scale;
   nsCOMPtr<nsIDeviceContext> dx;
   aPresContext.GetDeviceContext(getter_AddRefs(dx));
-  if (nsnull != dx) { 
+  if (dx) { 
     float sbWidth;
     float sbHeight;
     dx->GetCanonicalPixelScale(scale);
diff --git a/mozilla/layout/html/forms/src/nsSelectControlFrame.cpp b/mozilla/layout/html/forms/src/nsSelectControlFrame.cpp
index b90227db5b4..80f0dacea8f 100644
--- a/mozilla/layout/html/forms/src/nsSelectControlFrame.cpp
+++ b/mozilla/layout/html/forms/src/nsSelectControlFrame.cpp
@@ -356,7 +356,7 @@ nsSelectControlFrame::GetDesiredSize(nsIPresContext* aPresContext,
   float   scale;
   nsCOMPtr<nsIDeviceContext> dx;
   aPresContext->GetDeviceContext(getter_AddRefs(dx));
-  if (nsnull != dx) {
+  if (dx) {
     float sbWidth;
     float sbHeight;
     dx->GetCanonicalPixelScale(scale);
diff --git a/mozilla/layout/html/forms/src/nsTextControlFrame.cpp b/mozilla/layout/html/forms/src/nsTextControlFrame.cpp
index c9f9f48f57a..7467b68a8dd 100644
--- a/mozilla/layout/html/forms/src/nsTextControlFrame.cpp
+++ b/mozilla/layout/html/forms/src/nsTextControlFrame.cpp
@@ -273,7 +273,7 @@ nsTextControlFrame::GetDesiredSize(nsIPresContext* aPresContext,
     aPresContext->GetPixelsToTwips(&p2t);
     nsCOMPtr<nsIDeviceContext> dx;
     aPresContext->GetDeviceContext(getter_AddRefs(dx));
-    if (nsnull != dx) { 
+    if (dx) { 
       float sbWidth;
       float sbHeight;
       dx->GetCanonicalPixelScale(scale);
diff --git a/mozilla/layout/html/style/src/nsCSSStyleRule.cpp b/mozilla/layout/html/style/src/nsCSSStyleRule.cpp
index 32d9206d16d..12d291d2af6 100644
--- a/mozilla/layout/html/style/src/nsCSSStyleRule.cpp
+++ b/mozilla/layout/html/style/src/nsCSSStyleRule.cpp
@@ -1169,7 +1169,7 @@ void MapDeclarationInto(nsICSSDeclaration* aDeclaration,
         if (eCSSUnit_String == ourFont->mFamily.GetUnit()) {
           nsCOMPtr<nsIDeviceContext> dc;
           aPresContext->GetDeviceContext(getter_AddRefs(dc));
-          if (nsnull != dc) {
+          if (dc) {
             nsAutoString  familyList;
 
             ourFont->mFamily.GetStringValue(familyList);
diff --git a/mozilla/layout/style/nsCSSStyleRule.cpp b/mozilla/layout/style/nsCSSStyleRule.cpp
index 32d9206d16d..12d291d2af6 100644
--- a/mozilla/layout/style/nsCSSStyleRule.cpp
+++ b/mozilla/layout/style/nsCSSStyleRule.cpp
@@ -1169,7 +1169,7 @@ void MapDeclarationInto(nsICSSDeclaration* aDeclaration,
         if (eCSSUnit_String == ourFont->mFamily.GetUnit()) {
           nsCOMPtr<nsIDeviceContext> dc;
           aPresContext->GetDeviceContext(getter_AddRefs(dc));
-          if (nsnull != dc) {
+          if (dc) {
             nsAutoString  familyList;
 
             ourFont->mFamily.GetStringValue(familyList);
diff --git a/mozilla/layout/xml/document/src/nsXMLContentSink.cpp b/mozilla/layout/xml/document/src/nsXMLContentSink.cpp
index cff7be3cfc3..70a1da0d56d 100644
--- a/mozilla/layout/xml/document/src/nsXMLContentSink.cpp
+++ b/mozilla/layout/xml/document/src/nsXMLContentSink.cpp
@@ -230,7 +230,7 @@ nsXMLContentSink::DidBuildModel(PRInt32 aQualityLevel)
   PRInt32 i, ns = mDocument->GetNumberOfShells();
   for (i = 0; i < ns; i++) {
     nsCOMPtr<nsIPresShell> shell(mDocument->GetShellAt(i));
-    if (nsnull != shell) {
+    if (shell) {
       nsCOMPtr<nsIViewManager> vm;
       shell->GetViewManager(getter_AddRefs(vm));
       if(vm) {
@@ -1323,7 +1323,7 @@ nsXMLContentSink::StartLayout()
       // Now trigger a refresh
       nsCOMPtr<nsIViewManager> vm;
       shell->GetViewManager(getter_AddRefs(vm));
-      if (nsnull != vm) {
+      if (vm) {
         vm->EnableRefresh();
       }
 
@@ -1356,7 +1356,7 @@ nsXMLContentSink::StartLayout()
       if (nsnull != shell) {
         nsCOMPtr<nsIViewManager>vm;
         shell->GetViewManager(getter_AddRefs(vm));
-        if (nsnull != vm) {
+        if (vm) {
           nsIView* rootView = nsnull;
           vm->GetRootView(rootView);
           if (nsnull != rootView) {
diff --git a/mozilla/rdf/content/src/nsXULDocument.cpp b/mozilla/rdf/content/src/nsXULDocument.cpp
index d87a59ccb51..2725d3227a0 100644
--- a/mozilla/rdf/content/src/nsXULDocument.cpp
+++ b/mozilla/rdf/content/src/nsXULDocument.cpp
@@ -1145,7 +1145,7 @@ XULDocumentImpl::AddStyleSheet(nsIStyleSheet* aSheet)
             nsIPresShell* shell = NS_STATIC_CAST(nsIPresShell*, mPresShells[index]);
             nsCOMPtr<nsIStyleSet> set;
             shell->GetStyleSet(getter_AddRefs(set));
-            if (nsnull != set) {
+            if (set) {
                 set->AddDocStyleSheet(aSheet, this);
             }
         }
@@ -1174,7 +1174,7 @@ XULDocumentImpl::SetStyleSheetDisabledState(nsIStyleSheet* aSheet,
             nsIPresShell* shell = (nsIPresShell*)mPresShells.ElementAt(index);
             nsCOMPtr<nsIStyleSet> set;
             shell->GetStyleSet(getter_AddRefs(set));
-            if (nsnull != set) {
+            if (set) {
                 if (aDisabled) {
                     set->RemoveDocStyleSheet(aSheet);
                 }
@@ -2150,7 +2150,7 @@ XULDocumentImpl::StartLayout(void)
         // Now trigger a refresh
         nsCOMPtr<nsIViewManager> vm;
         shell->GetViewManager(getter_AddRefs(vm));
-        if (nsnull != vm) {
+        if (vm) {
             vm->EnableRefresh();
         }
 
diff --git a/mozilla/webshell/tests/viewer/nsBrowserWindow.cpp b/mozilla/webshell/tests/viewer/nsBrowserWindow.cpp
index 96baf0fdaf4..25316657209 100644
--- a/mozilla/webshell/tests/viewer/nsBrowserWindow.cpp
+++ b/mozilla/webshell/tests/viewer/nsBrowserWindow.cpp
@@ -655,7 +655,7 @@ NS_IMETHODIMP nsBrowserWindow::FindNext(const nsString &aSearchStr, PRBool aMatc
 	if (nsnull != shell) {
 	  nsCOMPtr<nsIDocument> doc;
     shell->GetDocument(getter_AddRefs(doc));
-	  if (nsnull != doc) {
+	  if (doc) {
 		  //PRBool foundIt = PR_FALSE;
 		  doc->FindNext(aSearchStr, aMatchCase, aSearchDown, aIsFound);
 		  if (!aIsFound) {
@@ -675,7 +675,7 @@ NS_IMETHODIMP nsBrowserWindow::ForceRefresh()
   if (nsnull != shell) {
     nsCOMPtr<nsIViewManager> vm;
     shell->GetViewManager(getter_AddRefs(vm));
-    if (nsnull != vm) {
+    if (vm) {
       nsIView* root;
       vm->GetRootView(root);
       if (nsnull != root) {
@@ -738,7 +738,7 @@ nsEventStatus nsBrowserWindow::ProcessDialogEvent(nsGUIEvent *aEvent)
 	    if (nsnull != shell) {
 	      nsCOMPtr<nsIDocument> doc;
         shell->GetDocument(getter_AddRefs(doc));
-	      if (nsnull != doc) {
+	      if (doc) {
           PRBool foundIt = PR_FALSE;
           doc->FindNext(searchStr, matchCase, findDwn, foundIt);
           if (!foundIt) {
@@ -1103,7 +1103,7 @@ nsBrowserWindow::DoSelectAll()
   if (nsnull != shell) {
     nsCOMPtr<nsIDocument> doc;
     shell->GetDocument(getter_AddRefs(doc));
-    if (nsnull != doc) {
+    if (doc) {
       doc->SelectAll();
       ForceRefresh();
     }
@@ -2154,7 +2154,7 @@ nsBrowserWindow::DoCopy()
   if (nsnull != shell) {
     nsCOMPtr<nsIDocument> doc;
     shell->GetDocument(getter_AddRefs(doc));
-    if (nsnull != doc) {
+    if (doc) {
       nsString buffer;
     
       nsIDOMSelection* sel = nsnull;
@@ -2594,7 +2594,7 @@ DumpContentRecurse(nsIWebShell* aWebShell, FILE* out)
     if (nsnull != shell) {
       nsCOMPtr<nsIDocument> doc;
       shell->GetDocument(getter_AddRefs(doc));
-      if (nsnull != doc) {
+      if (doc) {
         nsIContent* root = doc->GetRootContent();
         if (nsnull != root) {
 	        root->List(out);
@@ -2672,7 +2672,7 @@ DumpViewsRecurse(nsIWebShell* aWebShell, FILE* out)
     if (nsnull != shell) {
       nsCOMPtr<nsIViewManager> vm;
       shell->GetViewManager(getter_AddRefs(vm));
-      if (nsnull != vm) {
+      if (vm) {
 	      nsIView* root;
 	      vm->GetRootView(root);
 	      if (nsnull != root) {
@@ -2711,7 +2711,7 @@ nsBrowserWindow::DumpStyleSheets(FILE* out)
   if (nsnull != shell) {
     nsCOMPtr<nsIStyleSet> styleSet;
     shell->GetStyleSet(getter_AddRefs(styleSet));
-    if (nsnull == styleSet) {
+    if (!styleSet) {
       fputs("null style set\n", out);
     } else {
       styleSet->List(out);
@@ -2730,7 +2730,7 @@ nsBrowserWindow::DumpStyleContexts(FILE* out)
   if (nsnull != shell) {
     nsCOMPtr<nsIStyleSet> styleSet;
     shell->GetStyleSet(getter_AddRefs(styleSet));
-    if (nsnull == styleSet) {
+    if (!styleSet) {
       fputs("null style set\n", out);
     } else {
       nsIFrame* root;
@@ -2850,7 +2850,7 @@ nsBrowserWindow::DoDebugSave()
   if (nsnull != shell) {
     nsCOMPtr<nsIDocument> doc;
     shell->GetDocument(getter_AddRefs(doc));
-    if (nsnull != doc) {
+    if (doc) {
       nsString buffer;
 
       doc->CreateXIF(buffer);
@@ -2911,7 +2911,7 @@ nsBrowserWindow::DoToggleSelection()
   if (nsnull != shell) {
     nsCOMPtr<nsIDocument> doc;
     shell->GetDocument(getter_AddRefs(doc));
-    if (nsnull != doc) {
+    if (doc) {
       PRBool  current = doc->GetDisplaySelection();
       doc->SetDisplaySelection(!current);
       ForceRefresh();
@@ -3046,7 +3046,7 @@ nsBrowserWindow::DispatchStyleMenu(PRInt32 aID)
         nsAutoString  defaultStyle;
         nsCOMPtr<nsIDocument> doc;
         shell->GetDocument(getter_AddRefs(doc));
-        if (nsnull != doc) {
+        if (doc) {
           nsIAtom* defStyleAtom = NS_NewAtom("default-style");
           doc->GetHeaderData(defStyleAtom, defaultStyle);
           NS_RELEASE(defStyleAtom);
@@ -3084,7 +3084,7 @@ nsBrowserWindow::DispatchStyleMenu(PRInt32 aID)
       if (nsnull != shell) {
         nsCOMPtr<nsIDocument> doc;
         shell->GetDocument(getter_AddRefs(doc));
-        if (nsnull != doc) {
+        if (doc) {
           nsAutoString  defaultStyle;
           nsIAtom* defStyleAtom = NS_NewAtom("default-style");
           doc->GetHeaderData(defStyleAtom, defaultStyle);
diff --git a/mozilla/webshell/tests/viewer/nsViewerApp.cpp b/mozilla/webshell/tests/viewer/nsViewerApp.cpp
index 96edb09cd68..34ef1cdb6a6 100644
--- a/mozilla/webshell/tests/viewer/nsViewerApp.cpp
+++ b/mozilla/webshell/tests/viewer/nsViewerApp.cpp
@@ -967,7 +967,7 @@ nsViewerApp::CreateRobot(nsBrowserWindow* aWindow)
     if (nsnull != shell) {
       nsCOMPtr<nsIDocument> doc;
       shell->GetDocument(getter_AddRefs(doc));
-      if (nsnull!=doc) {
+      if (doc) {
         const char * str;
         nsresult rv = doc->GetDocumentURL()->GetSpec(&str);
         if (NS_FAILED(rv)) {
diff --git a/mozilla/webshell/tests/viewer/nsWebCrawler.cpp b/mozilla/webshell/tests/viewer/nsWebCrawler.cpp
index ba0d2d6e178..66c5c6eba91 100644
--- a/mozilla/webshell/tests/viewer/nsWebCrawler.cpp
+++ b/mozilla/webshell/tests/viewer/nsWebCrawler.cpp
@@ -263,7 +263,7 @@ nsWebCrawler:: EndLoadURL(nsIWebShell* aShell,
   if (nsnull != shell) {
     nsCOMPtr<nsIViewManager> vm;
     shell->GetViewManager(getter_AddRefs(vm));
-    if (nsnull != vm) {
+    if (vm) {
       nsIView* rootView;
       vm->GetRootView(rootView);
       vm->UpdateView(rootView, nsnull, NS_VMREFRESH_IMMEDIATE);
diff --git a/mozilla/webshell/tests/viewer/nsXPBaseWindow.cpp b/mozilla/webshell/tests/viewer/nsXPBaseWindow.cpp
index c097529a874..15096590845 100644
--- a/mozilla/webshell/tests/viewer/nsXPBaseWindow.cpp
+++ b/mozilla/webshell/tests/viewer/nsXPBaseWindow.cpp
@@ -271,7 +271,7 @@ void nsXPBaseWindow::ForceRefresh()
   if (nsnull != shell) {
     nsCOMPtr<nsIViewManager> vm;
     shell->GetViewManager(getter_AddRefs(vm));
-    if (nsnull != vm) {
+    if (vm) {
       nsIView* root;
       vm->GetRootView(root);
       if (nsnull != root) {
@@ -415,7 +415,7 @@ NS_IMETHODIMP nsXPBaseWindow::EndLoadURL(nsIWebShell* aShell, const PRUnichar* a
   if (nsnull != shell) {
     nsCOMPtr<nsIDocument> doc;
     shell->GetDocument(getter_AddRefs(doc));
-    if (nsnull != doc) {
+    if (doc) {
       mContentRoot = doc->GetRootContent();
       mDocIsLoaded = PR_TRUE;
       if (nsnull != mWindowListener) {
@@ -515,7 +515,7 @@ NS_IMETHODIMP nsXPBaseWindow::GetDocument(nsIDOMHTMLDocument *& aDocument)
   if (nsnull != shell) {
     nsCOMPtr<nsIDocument> doc;
     shell->GetDocument(getter_AddRefs(doc));
-    if (nsnull != doc) {
+    if (doc) {
       doc->QueryInterface(kIDOMHTMLDocumentIID,(void **)&htmlDoc);
     }
     NS_RELEASE(shell);