Revert "Re-land deferred compositing updates with fixed assumptions"

Source/core/rendering/RenderLayerScrollableArea.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 868 matching lines @@
         horizontalScrollbar->setFrameRect(hBarRect);
     }
 
     const IntRect& scrollCorner = scrollCornerRect();
     if (m_scrollCorner)
         m_scrollCorner->setFrameRect(scrollCorner);
 
     if (m_resizer)
         m_resizer->setFrameRect(resizerCornerRect(borderBox, ResizerForPointer));
 
-    // FIXME, this should eventually be removed, once we are certain that composited
-    // controls get correctly positioned on a compositor update. For now, conservatively
-    // leaving this unchanged.
     if (m_box->compositedLayerMapping())
         m_box->compositedLayerMapping()->positionOverflowControlsLayers(offsetFromRoot);
 }
 
+void RenderLayerScrollableArea::positionNewlyCreatedOverflowControls()
+{
+    if (!m_box->compositedLayerMapping()->hasUnpositionedOverflowControlsLayers())
+        return;
+
+    RenderGeometryMap geometryMap(UseTransforms);
+    RenderView* view = m_box->view();
+    if (this != view->layer()->scrollableArea() && m_box->layer()->parent())
+        geometryMap.pushMappingsToAncestor(m_box->layer()->parent(), 0);
+
+    LayoutPoint offsetFromRoot = LayoutPoint(geometryMap.absolutePoint(FloatPoint()));
+    positionOverflowControls(toIntSize(roundedIntPoint(offsetFromRoot)));
+}
+
 bool RenderLayerScrollableArea::scrollsOverflow() const
 {
     if (FrameView* frameView = m_box->view()->frameView())
         return frameView->containsScrollableArea(this);
 
     return false;
 }
 
 void RenderLayerScrollableArea::updateScrollCornerStyle()
 {
@@ skipping 533 matching lines @@
 bool RenderLayerScrollableArea::usesCompositedScrolling() const
 {
     // Scroll form controls on the main thread so they exhibit correct touch scroll event bubbling
     if (m_box && (m_box->isIntristicallyScrollable(VerticalScrollbar) || m_box->isIntristicallyScrollable(HorizontalScrollbar)))
         return false;
 
     return m_box->compositedLayerMapping() && m_box->compositedLayerMapping()->scrollingLayer();
 }
 
 } // Namespace WebCore