Optimize layout/repaint on FrameView resize

Source/core/rendering/RenderObject.cpp

Index: Source/core/rendering/RenderObject.cpp
diff --git a/Source/core/rendering/RenderObject.cpp b/Source/core/rendering/RenderObject.cpp
index 82c6a94c70ae77bd2f0b85075f29ad67cb1ab6a6..93c5f5b2c49bad7d5ad6842eb3731bf3cf2c738f 100644
--- a/Source/core/rendering/RenderObject.cpp
+++ b/Source/core/rendering/RenderObject.cpp
@@ -1622,7 +1622,7 @@ void RenderObject::repaintOverflowIfNeeded()
 
 bool RenderObject::checkForRepaint() const
 {
-    return !document().view()->needsFullRepaint() && !hasLayer() && everHadLayout();

[dsinclair, 2014/03/20 10:41:41]

Won't this end up triggering more invalidations? Previously if the view was
marked as doing a full repaint we'd skip issuing invalidations for children.
With this change, we'll always issue the child invalidations even if the full
renderView will be invalidated.

Should it be checking something like the needsRepaintLayout flag instead?

[Xianzhu, 2014/03/20 17:47:43]

It seems hard to weigh between full repaint and child repaints in
FrameView::layout(). In some cases we can be sure that full repaint is better
and mark full repaint. For other cases, perhaps we can fall back to full repaint
when number or area of child repaints exceeds some threshold during layout.
Good idea. I think this would help improve the situation. Would like to consider
it in some later change.

+    return !hasLayer() && everHadLayout();
 }
 
 bool RenderObject::checkForRepaintDuringLayout() const