Bug 578696 part 10. Stop holding strong refs when calling ContentInserted. r=sicking

content/base/public/nsIMutationObserver.h

@@ -234,6 +234,12 @@ public:
    *                   aDocument
    * @param aChild     The newly inserted child.
    * @param aIndexInContainer The index in the container of the new child.
+   *
+   * @note Callers of this method might not hold a strong reference to the
+   *       observer.  The observer is responsible for making sure it stays
+   *       alive for the duration of the call as needed.  The observer may
+   *       assume that this call will happen when there are script blockers on
+   *       the stack.
    */
   virtual void ContentInserted(nsIDocument *aDocument,
                                nsIContent* aContainer,

content/base/src/nsNodeUtils.cpp

@@ -183,7 +183,7 @@ nsNodeUtils::ContentInserted(nsINode* aContainer,
     document = static_cast<nsIDocument*>(aContainer);
   }
 
-  IMPL_STRONGREF_MUTATION_NOTIFICATION(ContentInserted, aContainer,
+  IMPL_MUTATION_NOTIFICATION(ContentInserted, aContainer,
                              (document, container, aChild, aIndexInContainer));
 }
 

content/xul/document/src/nsXULDocument.cpp

@@ -1121,6 +1121,9 @@ nsXULDocument::ContentInserted(nsIDocument* aDocument,
 {
     NS_ASSERTION(aDocument == this, "unexpected doc");
 
+    // Might not need this, but be safe for now.
+    nsCOMPtr<nsIMutationObserver> kungFuDeathGrip(this);
+
     AddSubtreeToDocument(aChild);
 }