Oilpan: improve ScrollableArea handling.

Source/core/frame/FrameHost.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 91 matching lines @@
 
 ConsoleMessageStorage& FrameHost::consoleMessageStorage() const
 {
     return *m_consoleMessageStorage;
 }
 
 DEFINE_TRACE(FrameHost)
 {
     visitor->trace(m_page);
     visitor->trace(m_topControls);
+    visitor->trace(m_pinchViewport);
     visitor->trace(m_eventHandlerRegistry);
     visitor->trace(m_consoleMessageStorage);
 }
 
 #if ENABLE(ASSERT)
 void checkFrameCountConsistency(int expectedFrameCount, Frame* frame)
 {
     ASSERT(expectedFrameCount >= 0);
 
     int actualFrameCount = 0;
@@ skipping 48 matching lines @@
 
     FrameView* rootView = page().deprecatedLocalMainFrame()->view();
 
     if (!rootView)
         return;
 
     rootView->setNeedsLayout();
 }
 
 }