Avoid layout/full-repaint on view height change if possible

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 3450 matching lines @@
 
     ScrollView::frameRectsChanged();
 }
 
 void FrameView::setLayoutSizeInternal(const IntSize& size)
 {
     if (m_layoutSize == size)
         return;
 
     m_layoutSize = size;
-    contentsResized();
+    ScrollView::contentsResized();

[ojan, 2014/01/03 02:04:26]

This deserves a comment as to why we're calling the ScrollView version instead
of the FrameView one. 

[Xianzhu, 2014/01/03 20:46:24]

Done.

+
+    if (RenderView* renderView = this->renderView()) {
+        renderView->viewResized();
+        if (!renderView->selfNeedsLayout())

[ojan, 2014/01/03 02:04:26]

This also deserves a comment explaining why we don't do this if the RenderView
needsLayout.

[Xianzhu, 2014/01/03 20:46:24]

Done.

+            sendResizeEventIfNeeded();
+    }
 }
 
 void FrameView::didAddScrollbar(Scrollbar* scrollbar, ScrollbarOrientation orientation)
 {
     ScrollableArea::didAddScrollbar(scrollbar, orientation);
     if (AXObjectCache* cache = axObjectCache())
         cache->handleScrollbarUpdate(this);
 }
 
 void FrameView::willRemoveScrollbar(Scrollbar* scrollbar, ScrollbarOrientation orientation)
 {
     ScrollableArea::willRemoveScrollbar(scrollbar, orientation);
     if (AXObjectCache* cache = axObjectCache()) {
         cache->remove(scrollbar);
         cache->handleScrollbarUpdate(this);
     }
 }
 
 } // namespace WebCore