update3dRenderingContext is 13.5% of GraphicsLayerUpdater::rebuildTree

Source/core/rendering/RenderLayer.cpp

Index: Source/core/rendering/RenderLayer.cpp
diff --git a/Source/core/rendering/RenderLayer.cpp b/Source/core/rendering/RenderLayer.cpp
index 20f618d211c61b254a05595db9ba40aaa1bb68a3..73d92be2aaaeac404f7d803b5af959360a795885 100644
--- a/Source/core/rendering/RenderLayer.cpp
+++ b/Source/core/rendering/RenderLayer.cpp
@@ -136,7 +136,6 @@ RenderLayer::RenderLayer(RenderLayerModelObject* renderer, LayerType type)
     , m_staticInlinePosition(0)
     , m_staticBlockPosition(0)
     , m_enclosingPaginationLayer(0)
-    , m_3dRenderingContextRoot(0)
     , m_groupedMapping(0)
     , m_repainter(renderer)
     , m_clipper(renderer)
@@ -562,20 +561,20 @@ void RenderLayer::updateTransform()
         dirty3DTransformedDescendantStatus();
 }
 
-// Note: this function assumes that all ancestors have an updated 3d rendering context root.
-void RenderLayer::update3dRenderingContext()
+RenderLayer* RenderLayer::renderingContextRoot()
 {
-    m_3dRenderingContextRoot = 0;
-
     if (!shouldFlattenTransform())
-        m_3dRenderingContextRoot = this;
+        return this;
 
+    // FIXME: Why doesn't this need to be a loop?

[ojan, 2014/03/25 01:36:00]

Yeah, this seems like it can't possibly be correct. :(

     if (RenderObject* containingBlock = renderer()->containingBlock()) {
         if (RenderLayer* ancestorLayer = containingBlock->enclosingLayer()) {
             if (!ancestorLayer->shouldFlattenTransform())
-                m_3dRenderingContextRoot = ancestorLayer->renderingContextRoot();
+                return ancestorLayer;
         }
     }
+
+    return 0;
 }
 
 TransformationMatrix RenderLayer::currentTransform(RenderStyle::ApplyTransformOrigin applyOrigin) const