diff --git a/mozilla/browser/components/bookmarks/src/Makefile.in b/mozilla/browser/components/bookmarks/src/Makefile.in
index 69fbb50fac5..57fced35a99 100644
--- a/mozilla/browser/components/bookmarks/src/Makefile.in
+++ b/mozilla/browser/components/bookmarks/src/Makefile.in
@@ -59,6 +59,7 @@ REQUIRES	= xpcom \
 		  dom \
 		  docshell \
 		  content \
+		  layout \
 		  htmlparser \
 		  intl \
 		  windowwatcher \
diff --git a/mozilla/content/base/public/nsIDocument.h b/mozilla/content/base/public/nsIDocument.h
index c00723b461b..07e401b2d3f 100644
--- a/mozilla/content/base/public/nsIDocument.h
+++ b/mozilla/content/base/public/nsIDocument.h
@@ -49,6 +49,7 @@
 #include "nsCRT.h"
 #include "mozFlushType.h"
 #include "nsIAtom.h"
+#include "nsCompatibility.h"
 
 class nsIContent;
 class nsPresContext;
@@ -91,8 +92,8 @@ class nsIDocumentObserver;
 
 // IID for the nsIDocument interface
 #define NS_IDOCUMENT_IID      \
-{ 0xb138a9aa, 0x3d0d, 0x4d0b, \
- { 0x98, 0x02, 0x72, 0x15, 0x54, 0x27, 0xe0, 0x2e } }
+{ 0x0b8acf09, 0x7877, 0x4928, \
+ { 0x8b, 0xfb, 0x6d, 0x7c, 0x6d, 0x53, 0xff, 0x32 } }
 
 // Flag for AddStyleSheet().
 #define NS_STYLESHEET_FROM_CATALOG                (1 << 0)
@@ -112,6 +113,7 @@ public:
     : nsINode(nsnull),
       mCharacterSet(NS_LITERAL_CSTRING("ISO-8859-1")),
       mNodeInfoManager(nsnull),
+      mCompatMode(eCompatibility_FullStandards),
       mIsInitialDocumentInWindow(PR_FALSE),
       mPartID(0)
   {
@@ -814,6 +816,13 @@ public:
    */
   virtual void ClearBoxObjectFor(nsIContent *aContent) = 0;
 
+  /**
+   * Get the compatibility mode for this document
+   */
+  nsCompatibility GetCompatibilityMode() const {
+    return mCompatMode;
+  }
+
 protected:
   ~nsIDocument()
   {
@@ -851,6 +860,9 @@ protected:
   // Table of element properties for this document.
   nsPropertyTable mPropertyTable;
 
+  // Compatibility mode
+  nsCompatibility mCompatMode;
+
   // True if BIDI is enabled.
   PRPackedBool mBidiEnabled;
 
diff --git a/mozilla/content/base/src/nsAttrValue.cpp b/mozilla/content/base/src/nsAttrValue.cpp
index 6e62cb4e240..9e8be91fd5f 100644
--- a/mozilla/content/base/src/nsAttrValue.cpp
+++ b/mozilla/content/base/src/nsAttrValue.cpp
@@ -956,9 +956,7 @@ nsAttrValue::ParseColor(const nsAString& aString, nsIDocument* aDocument)
   }
 
   // Check if we are in compatibility mode
-  // XXX evil NS_HexToRGB and NS_LooseHexToRGB take nsString as argument!
-  nsCOMPtr<nsIHTMLDocument> doc(do_QueryInterface(aDocument));
-  if (doc && doc->GetCompatibilityMode() == eCompatibility_NavQuirks) {
+  if (aDocument->GetCompatibilityMode() == eCompatibility_NavQuirks) {
     NS_LooseHexToRGB(colorStr, &color);
   }
   else {
diff --git a/mozilla/content/base/src/nsContentUtils.cpp b/mozilla/content/base/src/nsContentUtils.cpp
index 6c7813068a7..e46a2e31f00 100644
--- a/mozilla/content/base/src/nsContentUtils.cpp
+++ b/mozilla/content/base/src/nsContentUtils.cpp
@@ -3209,23 +3209,19 @@ nsContentUtils::CreateContextualFragment(nsIDOMNode* aContextNode,
       parser->SetContentSink(contentsink);
 
       nsDTDMode mode = eDTDMode_autodetect;
-      if (bHTML) {
-        switch (htmlDoc->GetCompatibilityMode()) {
-          case eCompatibility_NavQuirks:
-            mode = eDTDMode_quirks;
-            break;
-          case eCompatibility_AlmostStandards:
-            mode = eDTDMode_almost_standards;
-            break;
-          case eCompatibility_FullStandards:
-            mode = eDTDMode_full_standards;
-            break;
-          default:
-            NS_NOTREACHED("unknown mode");
-            break;
-        }
-      } else {
-        mode = eDTDMode_full_standards;
+      switch (document->GetCompatibilityMode()) {
+        case eCompatibility_NavQuirks:
+          mode = eDTDMode_quirks;
+          break;
+        case eCompatibility_AlmostStandards:
+          mode = eDTDMode_almost_standards;
+          break;
+        case eCompatibility_FullStandards:
+          mode = eDTDMode_full_standards;
+          break;
+        default:
+          NS_NOTREACHED("unknown mode");
+          break;
       }
       rv = parser->ParseFragment(aFragment, nsnull, tagStack,
                                  !bHTML, contentType, mode);
diff --git a/mozilla/content/html/content/src/nsGenericHTMLElement.cpp b/mozilla/content/html/content/src/nsGenericHTMLElement.cpp
index f1c93637a88..a08ce65c5fd 100644
--- a/mozilla/content/html/content/src/nsGenericHTMLElement.cpp
+++ b/mozilla/content/html/content/src/nsGenericHTMLElement.cpp
@@ -1340,12 +1340,7 @@ nsGenericHTMLElement::SetSpellcheck(PRBool aSpellcheck)
 PRBool
 nsGenericHTMLElement::InNavQuirksMode(nsIDocument* aDoc)
 {
-  nsCOMPtr<nsIHTMLDocument> doc(do_QueryInterface(aDoc));
-  if (!doc) {
-    return PR_FALSE;
-  }
-
-  return doc->GetCompatibilityMode() == eCompatibility_NavQuirks;
+  return aDoc && aDoc->GetCompatibilityMode() == eCompatibility_NavQuirks;
 }
 
 nsresult
diff --git a/mozilla/content/html/content/src/nsHTMLFrameSetElement.cpp b/mozilla/content/html/content/src/nsHTMLFrameSetElement.cpp
index 5f4671e51f3..13948eed3aa 100644
--- a/mozilla/content/html/content/src/nsHTMLFrameSetElement.cpp
+++ b/mozilla/content/html/content/src/nsHTMLFrameSetElement.cpp
@@ -336,12 +336,7 @@ nsHTMLFrameSetElement::ParseRowCol(const nsAString & aValue,
   }
 
   // Pre-grab the compat mode; we may need it later in the loop.
-  nsCompatibility mode = eCompatibility_FullStandards;
-  nsCOMPtr<nsIHTMLDocument> htmlDocument =
-    do_QueryInterface(GetOwnerDoc());
-  if (htmlDocument) {
-    mode = htmlDocument->GetCompatibilityMode();
-  }
+  PRBool isInQuirks = InNavQuirksMode(GetOwnerDoc());
       
   // Parse each comma separated token
 
@@ -398,7 +393,7 @@ nsHTMLFrameSetElement::ParseRowCol(const nsAString & aValue,
       }
 
       // Treat 0* as 1* in quirks mode (bug 40383)
-      if (eCompatibility_NavQuirks == mode) {
+      if (isInQuirks) {
         if ((eFramesetUnit_Relative == specs[i].mUnit) &&
           (0 == specs[i].mValue)) {
           specs[i].mValue = 1;
@@ -409,7 +404,7 @@ nsHTMLFrameSetElement::ParseRowCol(const nsAString & aValue,
       // Nav resized absolute and relative frames to "1" and
       // percent frames to an even percentage of the width
       //
-      //if ((eCompatibility_NavQuirks == aMode) && (specs[i].mValue <= 0)) {
+      //if (isInQuirks && (specs[i].mValue <= 0)) {
       //  if (eFramesetUnit_Percent == specs[i].mUnit) {
       //    specs[i].mValue = 100 / count;
       //  } else {
diff --git a/mozilla/content/html/document/src/nsHTMLDocument.cpp b/mozilla/content/html/document/src/nsHTMLDocument.cpp
index 1cf65aa3949..1f2389d876b 100644
--- a/mozilla/content/html/document/src/nsHTMLDocument.cpp
+++ b/mozilla/content/html/document/src/nsHTMLDocument.cpp
@@ -324,7 +324,6 @@ IdAndNameHashInitEntry(PLDHashTable *table, PLDHashEntryHdr *entry,
 
 nsHTMLDocument::nsHTMLDocument()
   : nsDocument("text/html"),
-    mCompatMode(eCompatibility_NavQuirks),
     mDefaultNamespaceID(kNameSpaceID_None)
 {
 
@@ -332,6 +331,7 @@ nsHTMLDocument::nsHTMLDocument()
   // bother initializing members to 0.
 
   mDefaultElementType = kNameSpaceID_XHTML;
+  mCompatMode = eCompatibility_NavQuirks;
 }
 
 nsHTMLDocument::~nsHTMLDocument()
@@ -1164,12 +1164,6 @@ nsHTMLDocument::GetImageMap(const nsAString& aMapName)
   return firstMatch;
 }
 
-nsCompatibility
-nsHTMLDocument::GetCompatibilityMode()
-{
-  return mCompatMode;
-}
-
 void
 nsHTMLDocument::SetCompatibilityMode(nsCompatibility aMode)
 {
@@ -1182,7 +1176,7 @@ nsHTMLDocument::SetCompatibilityMode(nsCompatibility aMode)
   if (shell) {
     nsPresContext *pc = shell->GetPresContext();
     if (pc) {
-      pc->SetCompatibilityMode(mCompatMode);
+      pc->CompatibilityModeChanged();
     }
   }
 }
diff --git a/mozilla/content/html/document/src/nsHTMLDocument.h b/mozilla/content/html/document/src/nsHTMLDocument.h
index b0a216e2eaf..1c595802749 100644
--- a/mozilla/content/html/document/src/nsHTMLDocument.h
+++ b/mozilla/content/html/document/src/nsHTMLDocument.h
@@ -107,7 +107,6 @@ public:
 
   virtual nsIDOMHTMLMapElement *GetImageMap(const nsAString& aMapName);
 
-  virtual nsCompatibility GetCompatibilityMode();
   virtual void SetCompatibilityMode(nsCompatibility aMode);
 
   virtual PRBool IsWriting()
@@ -256,8 +255,6 @@ protected:
     return mDefaultNamespaceID;
   };
 
-  nsCompatibility mCompatMode;
-
   nsCOMArray<nsIDOMHTMLMapElement> mImageMaps;
 
   nsCOMPtr<nsIDOMHTMLCollection> mImages;
diff --git a/mozilla/content/html/document/src/nsIHTMLDocument.h b/mozilla/content/html/document/src/nsIHTMLDocument.h
index 79148ee3185..6f01e2c3112 100644
--- a/mozilla/content/html/document/src/nsIHTMLDocument.h
+++ b/mozilla/content/html/document/src/nsIHTMLDocument.h
@@ -55,8 +55,8 @@ class nsIDOMHTMLBodyElement;
 class nsIScriptElement;
 
 #define NS_IHTMLDOCUMENT_IID \
-{ 0x43eec0b4, 0xd867, 0x4972, \
- { 0x8f, 0x64, 0x71, 0x9a, 0xc2, 0x45, 0x19, 0x3d } }
+{ 0xcfe72003, 0xcc90, 0x4624, \
+ { 0xb4, 0x1b, 0xc3, 0x14, 0x1d, 0x31, 0x7a, 0x71 } }
 
 
 /**
@@ -74,9 +74,8 @@ public:
   virtual void RemoveImageMap(nsIDOMHTMLMapElement* aMap) = 0;
 
   /**
-   * Access compatibility mode for this document
+   * Set compatibility mode for this document
    */
-  virtual nsCompatibility GetCompatibilityMode() = 0;
   virtual void SetCompatibilityMode(nsCompatibility aMode) = 0;
 
   virtual nsresult ResolveName(const nsAString& aName,
diff --git a/mozilla/dom/src/base/nsDOMClassInfo.cpp b/mozilla/dom/src/base/nsDOMClassInfo.cpp
index c4a2f052694..594b2ce7f5a 100644
--- a/mozilla/dom/src/base/nsDOMClassInfo.cpp
+++ b/mozilla/dom/src/base/nsDOMClassInfo.cpp
@@ -4096,8 +4096,10 @@ nsWindowSH::GlobalScopePolluterNewResolve(JSContext *cx, JSObject *obj,
   }
 
   nsIHTMLDocument *doc = (nsIHTMLDocument *)::JS_GetPrivate(cx, obj);
+  nsCOMPtr<nsIDocument> document(do_QueryInterface(doc));
 
-  if (!doc || doc->GetCompatibilityMode() != eCompatibility_NavQuirks) {
+  if (!document ||
+      document->GetCompatibilityMode() != eCompatibility_NavQuirks) {
     // If we don't have a document, or if the document is not in
     // quirks mode, return early.
 
@@ -8591,7 +8593,7 @@ nsHTMLDocumentSH::NewResolve(nsIXPConnectWrappedNative *wrapper, JSContext *cx,
 
     if (id == sAll_id && !sDisableDocumentAllSupport &&
         !ObjectIsNativeWrapper(cx, obj)) {
-      nsCOMPtr<nsIHTMLDocument> doc(do_QueryWrappedNative(wrapper));
+      nsCOMPtr<nsIDocument> doc(do_QueryWrappedNative(wrapper));
 
       if (doc->GetCompatibilityMode() == eCompatibility_NavQuirks) {
         JSObject *helper =
diff --git a/mozilla/extensions/webservices/soap/src/Makefile.in b/mozilla/extensions/webservices/soap/src/Makefile.in
index 758bd81f95b..7156ef21cc2 100644
--- a/mozilla/extensions/webservices/soap/src/Makefile.in
+++ b/mozilla/extensions/webservices/soap/src/Makefile.in
@@ -54,6 +54,7 @@ REQUIRES	= xpcom \
 		  necko \
 		  xmlextras \
 		  content \
+		  layout \
 		  widget \
 		  $(NULL)
 
diff --git a/mozilla/extensions/xmlextras/tests/Makefile.in b/mozilla/extensions/xmlextras/tests/Makefile.in
index 9d5b6c41f6b..09b790bfb90 100644
--- a/mozilla/extensions/xmlextras/tests/Makefile.in
+++ b/mozilla/extensions/xmlextras/tests/Makefile.in
@@ -48,6 +48,7 @@ REQUIRES	= xpcom \
 		  necko \
 		  dom \
 		  content \
+		  layout \
 		  widget \
 		  $(NULL)
 
diff --git a/mozilla/intl/chardet/src/Makefile.in b/mozilla/intl/chardet/src/Makefile.in
index 3565ff4c867..f8cd8d91b6f 100644
--- a/mozilla/intl/chardet/src/Makefile.in
+++ b/mozilla/intl/chardet/src/Makefile.in
@@ -59,6 +59,7 @@ REQUIRES	= xpcom \
 		  necko \
 		  widget \
 		  content \
+		  layout \
 		  dom \
 		  $(NULL)
 
diff --git a/mozilla/layout/base/nsPresContext.cpp b/mozilla/layout/base/nsPresContext.cpp
index ce46c0cfc8a..0115c15afdb 100644
--- a/mozilla/layout/base/nsPresContext.cpp
+++ b/mozilla/layout/base/nsPresContext.cpp
@@ -162,7 +162,6 @@ nsPresContext::nsPresContext(nsIDocument* aDocument, nsPresContextType aType)
   : mType(aType), mDocument(aDocument), mTextZoom(1.0),
     mPageSize(-1, -1),
     mViewportStyleOverflow(NS_STYLE_OVERFLOW_AUTO, NS_STYLE_OVERFLOW_AUTO),
-    mCompatibilityMode(eCompatibility_FullStandards),
     mImageAnimationModePref(imgIContainer::kNormalAnimMode),
     mDefaultVariableFont("serif", NS_FONT_STYLE_NORMAL, NS_FONT_VARIANT_NORMAL,
                          NS_FONT_WEIGHT_NORMAL, 0, NSIntPointsToTwips(12)),
@@ -891,16 +890,14 @@ nsPresContext::RootPresContext()
 }
 
 void
-nsPresContext::SetCompatibilityMode(nsCompatibility aMode)
+nsPresContext::CompatibilityModeChanged()
 {
-  mCompatibilityMode = aMode;
-
   if (!mShell)
     return;
 
   // enable/disable the QuirkSheet
   mShell->StyleSet()->
-    EnableQuirkStyleSheet(mCompatibilityMode == eCompatibility_NavQuirks);
+    EnableQuirkStyleSheet(CompatibilityMode() == eCompatibility_NavQuirks);
 }
 
 // Helper function for setting Anim Mode on image
diff --git a/mozilla/layout/base/nsPresContext.h b/mozilla/layout/base/nsPresContext.h
index 9b05c3a593f..7f329902edf 100644
--- a/mozilla/layout/base/nsPresContext.h
+++ b/mozilla/layout/base/nsPresContext.h
@@ -44,7 +44,6 @@
 #include "nsColor.h"
 #include "nsCoord.h"
 #include "nsAString.h"
-#include "nsCompatibility.h"
 #include "nsCOMPtr.h"
 #include "nsIPresShell.h"
 #include "nsRect.h"
@@ -199,13 +198,16 @@ public:
 #endif
 
   /**
-   * Access compatibility mode for this context
-   *
-   * All users must explicitly set the compatibility mode rather than
-   * relying on a default.
+   * Access compatibility mode for this context.  This is the same as
+   * our document's compatibility mode.
    */
-  nsCompatibility CompatibilityMode() const { return mCompatibilityMode; }
-  NS_HIDDEN_(void) SetCompatibilityMode(nsCompatibility aMode);
+  nsCompatibility CompatibilityMode() const {
+    return Document()->GetCompatibilityMode();
+  }
+  /**
+   * Notify the context that the document's compatibility mode has changed
+   */
+  NS_HIDDEN_(void) CompatibilityModeChanged();
 
   /**
    * Access the image animation mode for this context
@@ -759,7 +761,6 @@ protected:
   ScrollbarStyles       mViewportStyleOverflow;
   PRUint8               mFocusRingWidth;
 
-  nsCompatibility       mCompatibilityMode;
   PRUint16              mImageAnimationMode;
   PRUint16              mImageAnimationModePref;
 
diff --git a/mozilla/layout/base/nsPresShell.cpp b/mozilla/layout/base/nsPresShell.cpp
index ab0c3342fe7..dde9fd5cc22 100644
--- a/mozilla/layout/base/nsPresShell.cpp
+++ b/mozilla/layout/base/nsPresShell.cpp
@@ -1778,9 +1778,10 @@ PresShell::Init(nsIDocument* aDocument,
   // want to delete it in our destructor.
   mStyleSet = aStyleSet;
 
-  // Set the compatibility mode after attaching the pres context and
-  // style set, but before creating any frames.
-  mPresContext->SetCompatibilityMode(aCompatMode);
+  // Notify our prescontext that it now has a compatibility mode.  Note that
+  // this MUST happen after we set up our style set but before we create any
+  // frames.
+  mPresContext->CompatibilityModeChanged();
 
   // setup the preference style rules (no forced reflow), and do it
   // before creating any frames.
diff --git a/mozilla/xpfe/components/directory/Makefile.in b/mozilla/xpfe/components/directory/Makefile.in
index 708819e156b..9eb1ba8506b 100644
--- a/mozilla/xpfe/components/directory/Makefile.in
+++ b/mozilla/xpfe/components/directory/Makefile.in
@@ -53,6 +53,7 @@ REQUIRES	= xpcom \
 		  necko \
 		  rdf \
 		  content \
+		  layout \
 		  js \
 		  xpconnect \
 		  docshell \
diff --git a/mozilla/xpfe/components/directory/nsDirectoryViewer.cpp b/mozilla/xpfe/components/directory/nsDirectoryViewer.cpp
index 3b67f7cab32..9ee4a3e5b55 100644
--- a/mozilla/xpfe/components/directory/nsDirectoryViewer.cpp
+++ b/mozilla/xpfe/components/directory/nsDirectoryViewer.cpp
@@ -91,6 +91,7 @@
 #include "nsIStreamConverterService.h"
 #include "nsICategoryManager.h"
 #include "nsXPCOMCID.h"
+#include "nsIDocument.h"
 
 static const int FORMAT_HTML = 2;
 static const int FORMAT_XUL = 3;
diff --git a/mozilla/xpfe/components/directory/nsDirectoryViewer.h b/mozilla/xpfe/components/directory/nsDirectoryViewer.h
index 3e179bf0350..ff8f11f3ac8 100644
--- a/mozilla/xpfe/components/directory/nsDirectoryViewer.h
+++ b/mozilla/xpfe/components/directory/nsDirectoryViewer.h
@@ -43,7 +43,6 @@
 #include "nsNetUtil.h"
 #include "nsIStreamListener.h"
 #include "nsIContentViewer.h"
-#include "nsIDocument.h"
 #ifdef MOZ_RDF
 #include "nsIHTTPIndex.h"
 #include "nsIRDFService.h"