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

Source/core/frame/FrameView.cpp

Index: Source/core/frame/FrameView.cpp
diff --git a/Source/core/frame/FrameView.cpp b/Source/core/frame/FrameView.cpp
index 7a0bc2627cdb397039f409f18b67e3ffe136932f..bb6aa76c4fadea6ef103c1062d2f00b5bc679621 100644
--- a/Source/core/frame/FrameView.cpp
+++ b/Source/core/frame/FrameView.cpp
@@ -3468,7 +3468,13 @@ void FrameView::setLayoutSizeInternal(const IntSize& 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)