diff --git a/mozilla/content/base/public/nsIDocument.h b/mozilla/content/base/public/nsIDocument.h
index abb77b0d651..fdb774dc7cc 100644
--- a/mozilla/content/base/public/nsIDocument.h
+++ b/mozilla/content/base/public/nsIDocument.h
@@ -41,6 +41,7 @@
 #include "nsStringGlue.h"
 #include "nsIDocumentObserver.h" // for nsUpdateType
 #include "nsCOMPtr.h"
+#include "nsCOMArray.h"
 #include "nsIURI.h"
 #include "nsWeakPtr.h"
 #include "nsIWeakReferenceUtils.h"
@@ -95,8 +96,8 @@ class mozAutoSubtreeModified;
 
 // IID for the nsIDocument interface
 #define NS_IDOCUMENT_IID      \
-{ 0x6700e22b, 0x95b8, 0x44cf, \
-  { 0x8f, 0x5a, 0x57, 0x2c, 0x14, 0x5b, 0xd1, 0xa1 } }
+{ 0x9a26d0aa, 0x37d2, 0x4313, \
+  { 0x9e, 0x53, 0x16, 0xd1, 0xa4, 0x67, 0xb3, 0x5b } }
 
 
 // Flag for AddStyleSheet().
@@ -853,7 +854,12 @@ public:
    *
    * @param aTarget is the target for the mutation event.
    */
-  virtual void MayDispatchMutationEvent(nsINode* aTarget) = 0;
+  void MayDispatchMutationEvent(nsINode* aTarget)
+  {
+    if (mSubtreeModifiedDepth > 0) {
+      mSubtreeModifiedTargets.AppendObject(aTarget);
+    }
+  }
 
   /**
    * Marks as not-going-to-be-collected for the given generation of
@@ -962,6 +968,9 @@ protected:
   PRUint32 mMarkedCCGeneration;
 
   nsTObserverArray<nsIPresShell> mPresShells;
+
+  nsCOMArray<nsINode> mSubtreeModifiedTargets;
+  PRUint32            mSubtreeModifiedDepth;
 };
 
 NS_DEFINE_STATIC_IID_ACCESSOR(nsIDocument, NS_IDOCUMENT_IID)
diff --git a/mozilla/content/base/src/nsDocument.cpp b/mozilla/content/base/src/nsDocument.cpp
index 8d2fdd09fe9..92b5d716dc9 100644
--- a/mozilla/content/base/src/nsDocument.cpp
+++ b/mozilla/content/base/src/nsDocument.cpp
@@ -5756,14 +5756,6 @@ nsDocument::OnPageHide(PRBool aPersisted)
   mVisible = PR_FALSE;
 }
 
-void
-nsDocument::MayDispatchMutationEvent(nsINode* aTarget)
-{
-  if (mSubtreeModifiedDepth > 0) {
-    mSubtreeModifiedTargets.AppendObject(aTarget);
-  }
-}
-
 void
 nsDocument::WillDispatchMutationEvent(nsINode* aTarget)
 {
diff --git a/mozilla/content/base/src/nsDocument.h b/mozilla/content/base/src/nsDocument.h
index fc7c35c5e4b..482458da657 100644
--- a/mozilla/content/base/src/nsDocument.h
+++ b/mozilla/content/base/src/nsDocument.h
@@ -73,7 +73,6 @@
 #include "nsINodeInfo.h"
 #include "nsIDOMDocumentEvent.h"
 #include "nsIDOM3DocumentEvent.h"
-#include "nsCOMArray.h"
 #include "nsHashtable.h"
 #include "nsInterfaceHashtable.h"
 #include "nsIBoxObject.h"
@@ -507,7 +506,6 @@ public:
   virtual void OnPageShow(PRBool aPersisted);
   virtual void OnPageHide(PRBool aPersisted);
   
-  virtual void MayDispatchMutationEvent(nsINode* aTarget);
   virtual void WillDispatchMutationEvent(nsINode* aTarget);
   virtual void MutationEventDispatched(nsINode* aTarget);
 
@@ -819,9 +817,6 @@ private:
   // Member to store out last-selected stylesheet set.
   nsString mLastStyleSheetSet;
 
-  nsCOMArray<nsINode> mSubtreeModifiedTargets;
-  PRUint32            mSubtreeModifiedDepth;
-
   // Our update nesting level
   PRUint32 mUpdateNestLevel;
 };