[WIP] Adding support for <iframe>s to slimming paint.

Source/core/frame/Frame.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Simon Hausmann <hausmann@kde.org>
  *                     2000 Stefan Schimanski <1Stein@gmx.de>
  *                     2001 George Staikos <staikos@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2005 Alexey Proskuryakov <ap@nypop.com>
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
@@ skipping 114 matching lines @@
 {
     if (isRemoteFrame())
         return false;
 
     if (!tree().parent())
         return true;
 
     return tree().parent()->isRemoteFrame();
 }
 
+LocalFrame* Frame::localRoot() const
+{
+    Frame* frame = const_cast<Frame*>(this);
+    while (frame && !frame->isLocalRoot())
+        frame = frame->tree().parent();
+    return toLocalFrame(frame);
+}
+
 HTMLFrameOwnerElement* Frame::deprecatedLocalOwner() const
 {
     return m_owner && m_owner->isLocal() ? toHTMLFrameOwnerElement(m_owner) : 0;
 }
 
 static ChromeClient& emptyChromeClient()
 {
     DEFINE_STATIC_LOCAL(EmptyChromeClient, client, ());
     return client;
 }
@@ skipping 57 matching lines @@
 
     if (m_owner) {
         if (m_owner->isLocal())
             toHTMLFrameOwnerElement(m_owner)->setContentFrame(*this);
     } else {
         page()->setMainFrame(this);
     }
 }
 
 } // namespace blink