Add Blink APIs for frame tree mirroring.

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 53 matching lines @@
     , m_remotePlatformLayer(0)
 {
     ASSERT(page());
 
 #ifndef NDEBUG
     frameCounter.increment();
 #endif
 
     if (m_owner) {
         page()->incrementSubframeCount();
-        if (m_owner->isLocal())
-            toHTMLFrameOwnerElement(m_owner)->setContentFrame(*this);
+        m_owner->setContentFrame(*this);
     }
 }
 
 Frame::~Frame()
 {
     disconnectOwnerElement();
     setDOMWindow(nullptr);
 
     // FIXME: We should not be doing all this work inside the destructor
 
@@ skipping 92 matching lines @@
 
 bool Frame::isMainFrame() const
 {
     Page* page = this->page();
     return page && this == page->mainFrame();
 }
 
 void Frame::disconnectOwnerElement()
 {
     if (m_owner) {
-        if (m_owner->isLocal())
-            toHTMLFrameOwnerElement(m_owner)->clearContentFrame();
+        m_owner->clearContentFrame();
         if (page())
             page()->decrementSubframeCount();
     }
     m_owner = 0;
 }
 
 } // namespace WebCore