Rework composited scrolling updates.

Source/WebCore/page/FrameView.cpp

Index: Source/WebCore/page/FrameView.cpp
diff --git a/Source/WebCore/page/FrameView.cpp b/Source/WebCore/page/FrameView.cpp
index 8e1e42f5815505767189a0b642e716325dfd1fc4..e30c734194df10c7dbf552a970a29501c8c35f0d 100644
--- a/Source/WebCore/page/FrameView.cpp
+++ b/Source/WebCore/page/FrameView.cpp
@@ -715,11 +715,12 @@ void FrameView::updateCompositingLayersAfterStyleChange()
         return;
 
     // This call will make sure the cached hasAcceleratedCompositing is updated from the pref
+    renderView->compositor()->updateLayoutDependentState();
     renderView->compositor()->cacheAcceleratedCompositingFlags();
     renderView->compositor()->updateCompositingLayers(CompositingUpdateAfterStyleChange);
 }
 
-void FrameView::updateCompositingLayersAfterLayout()
+void FrameView::updateCompositingLayersAfterLayoutAndPositioning()
 {
     RenderView* renderView = this->renderView();
     if (!renderView)
@@ -730,6 +731,15 @@ void FrameView::updateCompositingLayersAfterLayout()
     renderView->compositor()->updateCompositingLayers(CompositingUpdateAfterLayout);
 }
 
+void FrameView::updateCompositingLayersAfterLayout()
+{
+    RenderView* renderView = this->renderView();
+    if (!renderView)
+        return;
+
+    renderView->compositor()->updateLayoutDependentState();
+}
+
 bool FrameView::usesCompositedScrolling() const
 {
     RenderView* renderView = this->renderView();
@@ -1144,11 +1154,13 @@ void FrameView::layout(bool allowSubtree)
         root->view()->repaint(); // FIXME: This isn't really right, since the RenderView doesn't fully encompass the visibleContentRect(). It just happens
                                  // to work out most of the time, since first layouts and printing don't have you scrolled anywhere.
 
+    updateCompositingLayersAfterLayout();
+
     layer->updateLayerPositionsAfterLayout(renderView()->layer(), updateLayerPositionFlags(layer, subtree, m_doFullRepaint));
 
     endDeferredRepaints();
 
-    updateCompositingLayersAfterLayout();
+    updateCompositingLayersAfterLayoutAndPositioning();
 
     m_layoutCount++;