Remove document.rootScroller compositing clipping effects.

third_party/WebKit/Source/core/page/scrolling/RootScrollerController.cpp

Index: third_party/WebKit/Source/core/page/scrolling/RootScrollerController.cpp
diff --git a/third_party/WebKit/Source/core/page/scrolling/RootScrollerController.cpp b/third_party/WebKit/Source/core/page/scrolling/RootScrollerController.cpp
index 5c086312d890f9b33f5fe43964c128e1ec5add5d..1916ed23ae6e93289b4d424fec1c23113f7e5d87 100644
--- a/third_party/WebKit/Source/core/page/scrolling/RootScrollerController.cpp
+++ b/third_party/WebKit/Source/core/page/scrolling/RootScrollerController.cpp
@@ -105,23 +105,8 @@ void RootScrollerController::recomputeEffectiveRootScroller() {
       return;
   }
 
-  PaintLayer* oldRootScrollerLayer = rootScrollerPaintLayer();
-
   m_effectiveRootScroller = newEffectiveRootScroller;
 
-  // This change affects both the old and new layers.
-  if (oldRootScrollerLayer)
-    oldRootScrollerLayer->setNeedsCompositingInputsUpdate();
-  if (rootScrollerPaintLayer())
-    rootScrollerPaintLayer()->setNeedsCompositingInputsUpdate();
-
-  // The above may not be enough as we need to update existing ancestor
-  // GraphicsLayers. This will force us to rebuild the GraphicsLayer tree.
-  if (LayoutView* layoutView = m_document->layoutView()) {
-    layoutView->compositor()->setNeedsCompositingUpdate(
-        CompositingUpdateRebuildTree);
-  }
-
   if (Page* page = m_document->page())
     page->globalRootScrollerController().didChangeRootScroller();
 }