Remove CompositingUpdateOnScroll

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 1663 matching lines @@
     if (!hasViewportConstrainedObjects())
         return;
 
     RefPtr<FrameView> protect(this);
 
     // If there fixed position elements, scrolling may cause compositing layers to change.
     // Update widget and layer positions after scrolling, but only if we're not inside of
     // layout.
     if (!m_nestedLayoutCount) {
         updateWidgetPositions();
-        if (RenderView* renderView = this->renderView())
+        if (RenderView* renderView = this->renderView()) {
             renderView->layer()->updateLayerPositionsAfterDocumentScroll();
+            renderView->layer()->setNeedsToUpdateAncestorDependentProperties();
+            renderView->compositor()->setNeedsCompositingUpdate(CompositingUpdateAfterCompositingInputChange);
+        }
     }
-
-    // Compositing layers may change after scrolling.
-    // FIXME: Maybe no longer needed after we land squashing and kill overlap testing?
-    if (RenderView* renderView = this->renderView())
-        renderView->compositor()->setNeedsCompositingUpdate(CompositingUpdateOnScroll);
 }
 
 void FrameView::updateFixedElementPaintInvalidationRectsAfterScroll()
 {
     if (!hasViewportConstrainedObjects())
         return;
 
     // Update the paint invalidation rects for fixed elements after scrolling and invalidation to reflect
     // the new scroll position.
     ViewportConstrainedObjectSet::const_iterator end = m_viewportConstrainedObjects->end();
@@ skipping 1563 matching lines @@
 void FrameView::willRemoveScrollbar(Scrollbar* scrollbar, ScrollbarOrientation orientation)
 {
     ScrollableArea::willRemoveScrollbar(scrollbar, orientation);
     if (AXObjectCache* cache = axObjectCache()) {
         cache->remove(scrollbar);
         cache->handleScrollbarUpdate(this);
     }
 }
 
 } // namespace WebCore