Refactoring: Add toWebFrameImpl() interface.

Source/web/WebViewImpl.cpp

 /*
  * Copyright (C) 2011, 2012 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 2568 matching lines @@
 WebFrame* WebViewImpl::mainFrame()
 {
     return mainFrameImpl();
 }
 
 WebFrame* WebViewImpl::findFrameByName(
     const WebString& name, WebFrame* relativeToFrame)
 {
     if (!relativeToFrame)
         relativeToFrame = mainFrame();
-    Frame* frame = static_cast<WebFrameImpl*>(relativeToFrame)->frame();
+    Frame* frame = toWebFrameImpl(relativeToFrame)->frame();
     frame = frame->tree()->find(name);
     return WebFrameImpl::fromFrame(frame);
 }
 
 WebFrame* WebViewImpl::focusedFrame()
 {
     return WebFrameImpl::fromFrame(focusedWebCoreFrame());
 }
 
 void WebViewImpl::setFocusedFrame(WebFrame* frame)
 {
     if (!frame) {
         // Clears the focused frame if any.
         Frame* frame = focusedWebCoreFrame();
         if (frame)
             frame->selection()->setFocused(false);
         return;
     }
-    WebFrameImpl* frameImpl = static_cast<WebFrameImpl*>(frame);
-    Frame* webcoreFrame = frameImpl->frame();
+    Frame* webcoreFrame = toWebFrameImpl(frame)->frame();
     webcoreFrame->page()->focusController().setFocusedFrame(webcoreFrame);
 }
 
 void WebViewImpl::setInitialFocus(bool reverse)
 {
     if (!m_page)
         return;
     Frame* frame = page()->focusController().focusedOrMainFrame();
     if (Document* document = frame->document())
         document->setFocusedElement(0);
@@ skipping 1491 matching lines @@
 }
 
 bool WebViewImpl::shouldDisableDesktopWorkarounds()
 {
     ViewportArguments arguments = mainFrameImpl()->frame()->document()->viewportArguments();
     return arguments.width == ViewportArguments::ValueDeviceWidth || !arguments.userZoom
         || (arguments.minZoom == arguments.maxZoom && arguments.minZoom != ViewportArguments::ValueAuto);
 }
 
 } // namespace WebKit