Checking in a workaround for scrollbar code bug 55334, this bug causes scrollbars to not show up in pages that are completely generated with document.write(). r=brendan@mozilla.org/nisheeth@netscape.com, sr=vidur@netscape.com

content/html/document/src/nsHTMLContentSink.cpp

@@ -1389,9 +1389,6 @@ SinkContext::OpenContainer(const nsIParserNode& aNode)
   mStack[mStackPos].mInsertionPoint = -1;
   content->SetDocument(mSink->mDocument, PR_FALSE, PR_TRUE);
 
-  nsCOMPtr<nsIScriptGlobalObject> scriptGlobalObject;
-  mSink->mDocument->GetScriptGlobalObject(getter_AddRefs(scriptGlobalObject));
-
   rv = mSink->AddAttributes(aNode, content);
 
   if (mPreAppend) {
@@ -2356,14 +2353,25 @@ HTMLContentSink::Init(nsIDocument* aDoc,
   NS_ENSURE_SUCCESS(rv, rv);
 
   // Make root part
-  rv = NS_NewHTMLHtmlElement(&mRoot, nodeInfo);
-  if (NS_OK != rv) {
-    MOZ_TIMER_DEBUGLOG(("Stop: nsHTMLContentSink::Init()\n"));
-    MOZ_TIMER_STOP(mWatch);
-    return rv;
+
+  nsCOMPtr<nsIContent> doc_root(dont_AddRef(mDocument->GetRootContent()));
+
+  if (doc_root) {
+    // If the document already has a root we'll use it. This will
+    // happen when we do document.open()/.write()/.close()...
+
+    CallQueryInterface(doc_root, &mRoot);
+  } else {
+    rv = NS_NewHTMLHtmlElement(&mRoot, nodeInfo);
+    if (NS_OK != rv) {
+      MOZ_TIMER_DEBUGLOG(("Stop: nsHTMLContentSink::Init()\n"));
+      MOZ_TIMER_STOP(mWatch);
+      return rv;
+    }
+
+    mRoot->SetDocument(mDocument, PR_FALSE, PR_TRUE);
+    mDocument->SetRootContent(mRoot);
   }
-  mRoot->SetDocument(mDocument, PR_FALSE, PR_TRUE);
-  mDocument->SetRootContent(mRoot);
 
   // Make head part
   rv = mNodeInfoManager->GetNodeInfo(NS_ConvertASCIItoUCS2("head"),

content/html/document/src/nsHTMLDocument.cpp

@@ -2186,10 +2186,68 @@ nsHTMLDocument::OpenCommon(nsIURI* aSourceURL)
       return result;
   }
 
+  // XXX This is a nasty workaround for a scrollbar code bug
+  // (http://bugzilla.mozilla.org/show_bug.cgi?id=55334).
+
+  // Hold on to our root element
+  nsCOMPtr<nsIContent> root(mRootContent);
+
+  if (root) {
+    PRInt32 count;
+    root->ChildCount(count);
+
+    // Remove all the children from the root.
+    while (--count >= 0) {
+      root->RemoveChildAt(count, PR_TRUE);
+    }
+
+    count = 0;
+
+    mRootContent->GetAttributeCount(count);
+
+    // Remove all attributes from the root element
+    while (--count >= 0) {
+      nsCOMPtr<nsIAtom> name, prefix;
+      PRInt32 nsid;
+
+      root->GetAttributeNameAt(count, nsid, *getter_AddRefs(name),
+                               *getter_AddRefs(prefix));
+
+      root->UnsetAttribute(nsid, name, PR_FALSE);
+    }
+
+    // Remove the root from the childlist
+    if (mChildren) {
+      mChildren->RemoveElement(root);
+    }
+
+    mRootContent = nsnull;
+  }
+
+  // Call Reset(), this will now do the full reset, except removing
+  // the root from the document, doing that confuses the scrollbar
+  // code in mozilla since the document in the root element and all
+  // the anonymous content (i.e. scrollbar elements) is set to
+  // null.
+
   result = Reset(channel, group);
   if (NS_FAILED(result))
     return result;
 
+  if (root) {
+    // Tear down the frames for the root element.
+    ContentRemoved(nsnull, root, 0);
+
+    // Put the root element back into the document, we don't notify
+    // the document about this insertion since the sink will do that
+    // for us, the sink will call InitialReflow() and that'll create
+    // frames for the root element and the scrollbars work as expected
+    // (since the document in the root element was never set to null)
+
+    mChildren->AppendElement(root);
+    mRootContent = root;
+  }
+
   result = nsComponentManager::CreateInstance(kCParserCID, nsnull, 
                                               NS_GET_IID(nsIParser), 
                                               (void **)&mParser);