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 91a37524021e1d8c599965b0db2654ebe5726af7..d3d15c1c7b3d324fd7048e479dbfea13264021ee 100644
--- a/Source/core/frame/FrameView.cpp
+++ b/Source/core/frame/FrameView.cpp
@@ -3464,7 +3464,13 @@ void FrameView::setLayoutSizeInternal(const IntSize& size)
         return;
 
     m_layoutSize = size;
-    contentsResized();
+    ScrollView::contentsResized();
+
+    if (RenderView* renderView = this->renderView()) {
+        renderView->viewResized();
+        if (!renderView->selfNeedsLayout())
+            sendResizeEventIfNeeded();

[ojan, 2013/12/18 00:48:20]

Why do you need to change this as part of this patch?

[Xianzhu, 2013/12/18 20:22:45]

Before the change, FrameView::performPostLayoutTasks() will call
sendResizeEventIfNeeded() whenever the layout-size changes. With the optimized
layout-size-change path in this change, we must call it here otherwise nowhere
the resize event would be sent.

+    }
 }
 
 void FrameView::didAddScrollbar(Scrollbar* scrollbar, ScrollbarOrientation orientation)