Add Frame::isMainFrame and deploy it

Source/core/frame/FrameView.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 567 matching lines @@
 
     if (o->isSVGRoot()) {
         // overflow is ignored in stand-alone SVG documents.
         if (!toRenderSVGRoot(o)->isEmbeddedThroughFrameContainingSVGDocument())
             return;
         overflowX = OHIDDEN;
         overflowY = OHIDDEN;
     }
 
     bool ignoreOverflowHidden = false;
-    if (m_frame->settings()->ignoreMainFrameOverflowHiddenQuirk() && m_frame->page()->mainFrame() == m_frame)
+    if (m_frame->settings()->ignoreMainFrameOverflowHiddenQuirk() && m_frame->isMainFrame())
         ignoreOverflowHidden = true;
 
     switch (overflowX) {
         case OHIDDEN:
             if (!ignoreOverflowHidden)
                 hMode = ScrollbarAlwaysOff;
             break;
         case OSCROLL:
             hMode = ScrollbarAlwaysOn;
             break;
@@ skipping 2872 matching lines @@
 void FrameView::setCursor(const Cursor& cursor)
 {
     Page* page = frame().page();
     if (!page)
         return;
     page->chrome().setCursor(cursor);
 }
 
 bool FrameView::isMainFrame() const
 {
-    return m_frame->page() && m_frame->page()->mainFrame() == m_frame;
+    return m_frame->isMainFrame();
 }
 
 void FrameView::frameRectsChanged()
 {
     if (layoutSizeFixedToFrameSize())
         setLayoutSizeInternal(frameRect().size());
 
     ScrollView::frameRectsChanged();
 }
 
 void FrameView::setLayoutSizeInternal(const IntSize& size)
 {
     if (m_layoutSize == size)
         return;
 
     m_layoutSize = size;
     contentsResized();
 }
 
 } // namespace WebCore