Merge 120750 - Fix scrollbar layers being misplaced with a clipped owner layer

Source/WebCore/rendering/RenderLayerBacking.cpp

Index: Source/WebCore/rendering/RenderLayerBacking.cpp
===================================================================
--- Source/WebCore/rendering/RenderLayerBacking.cpp	(revision 120842)
+++ Source/WebCore/rendering/RenderLayerBacking.cpp	(working copy)
@@ -244,6 +244,10 @@
 
 bool RenderLayerBacking::shouldClipCompositedBounds() const
 {
+    // Scrollbar layers use this layer for relative positioning, so don't clip.
+    if (layerForHorizontalScrollbar() || layerForVerticalScrollbar())
+        return false;
+
     if (m_usingTiledCacheLayer)
         return true;