diff --git a/mozilla/docshell/base/nsDocShell.cpp b/mozilla/docshell/base/nsDocShell.cpp
index a40b0950276..36ae7c4dfe8 100644
--- a/mozilla/docshell/base/nsDocShell.cpp
+++ b/mozilla/docshell/base/nsDocShell.cpp
@@ -1248,21 +1248,17 @@ nsDocShell::GetEldestPresContext(nsPresContext** aPresContext)
 NS_IMETHODIMP
 nsDocShell::GetPresContext(nsPresContext ** aPresContext)
 {
-    nsresult rv = NS_OK;
-
     NS_ENSURE_ARG_POINTER(aPresContext);
     *aPresContext = nsnull;
 
-    if (mContentViewer) {
-        nsCOMPtr<nsIDocumentViewer> docv(do_QueryInterface(mContentViewer));
+    nsresult rv = EnsureContentViewer();
+    if (NS_FAILED(rv))
+      return rv;    // we're probably being destroyed
+    
+    nsCOMPtr<nsIDocumentViewer> docv(do_QueryInterface(mContentViewer));
+    NS_ENSURE_TRUE(docv, NS_ERROR_NO_INTERFACE);
 
-        if (docv) {
-            rv = docv->GetPresContext(aPresContext);
-        }
-    }
-
-    // Fail silently, if no PresContext is available...
-    return rv;
+    return docv->GetPresContext(aPresContext);
 }
 
 NS_IMETHODIMP
diff --git a/mozilla/dom/src/base/nsGlobalWindow.cpp b/mozilla/dom/src/base/nsGlobalWindow.cpp
index fc7dfdc17b4..5d7ea921dcc 100644
--- a/mozilla/dom/src/base/nsGlobalWindow.cpp
+++ b/mozilla/dom/src/base/nsGlobalWindow.cpp
@@ -4936,8 +4936,8 @@ nsGlobalWindow::Activate()
    NS_ENSURE_TRUE(widget, NS_ERROR_FAILURE);
 
    return widget->SetFocus();
-
  */
+
   nsCOMPtr<nsIBaseWindow> treeOwnerAsWin;
   GetTreeOwner(getter_AddRefs(treeOwnerAsWin));
   if (treeOwnerAsWin) {
@@ -4952,10 +4952,7 @@ nsGlobalWindow::Activate()
 
   nsCOMPtr<nsIPresShell> presShell;
   mDocShell->GetPresShell(getter_AddRefs(presShell));
-  if (!presShell) {
-    NS_WARNING( "no preshell for window" );
-    return NS_ERROR_FAILURE;
-  }
+  NS_ENSURE_TRUE(presShell, NS_ERROR_FAILURE);
 
   nsIViewManager* vm = presShell->GetViewManager();
   NS_ENSURE_TRUE(vm, NS_ERROR_FAILURE);
diff --git a/mozilla/embedding/browser/webBrowser/nsWebBrowser.cpp b/mozilla/embedding/browser/webBrowser/nsWebBrowser.cpp
index 4e5396eef51..283ae7cb073 100644
--- a/mozilla/embedding/browser/webBrowser/nsWebBrowser.cpp
+++ b/mozilla/embedding/browser/webBrowser/nsWebBrowser.cpp
@@ -1787,19 +1787,14 @@ NS_IMETHODIMP nsWebBrowser::Activate(void)
     if (mWWatch)
       mWWatch->SetActiveWindow(win);
 
-    /* Activate the window itself. Do this only if the PresShell has
-       been created, since DOMWindow->Activate asserts otherwise.
-       (This method can be called during window creation before
-       the PresShell exists. For ex, Windows apps responding to
-       WM_ACTIVATE). */
-    NS_ENSURE_STATE(mDocShell);
-    nsCOMPtr<nsIPresShell> presShell;
-    mDocShell->GetPresShell(getter_AddRefs(presShell));
-    if(presShell) {
-      nsCOMPtr<nsPIDOMWindow> privateDOMWindow = do_QueryInterface(win);
-      if(privateDOMWindow)
-        privateDOMWindow->Activate();
-    }
+    /* Activate the window itself. Note that this method can be called during
+       window creation before the PresShell exists (for ex, Windows apps
+       responding to WM_ACTIVATE), which case nsGlobalWindow::Activate()
+       will return early.
+    */
+    nsCOMPtr<nsPIDOMWindow> privateDOMWindow = do_QueryInterface(win);
+    if (privateDOMWindow)
+      privateDOMWindow->Activate();
   }
 
   mActivating = PR_FALSE;
@@ -1814,12 +1809,6 @@ NS_IMETHODIMP nsWebBrowser::Deactivate(void)
      This seems harmless and maybe safer, but we have no real evidence
      either way just yet. */
 
-  NS_ENSURE_STATE(mDocShell);
-  nsCOMPtr<nsIPresShell> presShell;
-  mDocShell->GetPresShell(getter_AddRefs(presShell));
-  if(!presShell)
-    return NS_OK;
-
   nsCOMPtr<nsIDOMWindow> domWindow;
   GetContentDOMWindow(getter_AddRefs(domWindow));
   if (domWindow) {