Change Page::m_mainFrame to be a Frame.

Source/web/tests/ViewportTest.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 109 matching lines @@
 static void setViewportSettings(WebSettings* settings)
 {
     settings->setViewportEnabled(true);
     settings->setViewportMetaEnabled(true);
     settings->setMainFrameResizesAreOrientationChanges(true);
 }
 
 static PageScaleConstraints runViewportTest(Page* page, int initialWidth, int initialHeight)
 {
     IntSize initialViewportSize(initialWidth, initialHeight);
-    page->mainFrame()->view()->setFrameRect(IntRect(IntPoint::zero(), initialViewportSize));
+    toLocalFrame(page->mainFrame())->view()->setFrameRect(IntRect(IntPoint::zero(), initialViewportSize));
     ViewportDescription description = page->viewportDescription();
     PageScaleConstraints constraints = description.resolve(initialViewportSize, WebCore::Length(980, WebCore::Fixed));
 
     constraints.fitToContentsWidth(constraints.layoutSize.width(), initialWidth);
     return constraints;
 }
 
 TEST_F(ViewportTest, viewport1)
 {
     UseMockScrollbarSettings mockScrollbarSettings;
@@ skipping 3056 matching lines @@
     FrameTestHelpers::WebViewHelper webViewHelper;
     webViewHelper.initializeAndLoad(m_baseURL + "viewport/viewport-warnings-7.html", true, &webFrameClient, 0, setViewportSettings);
 
     Page* page = webViewHelper.webViewImpl()->page();
     runViewportTest(page, 320, 352);
 
     EXPECT_EQ(0U, webFrameClient.messages.size());
 }
 
 } // namespace