update3dRenderingContext is 13.5% of GraphicsLayerUpdater::rebuildTree

Source/core/rendering/RenderLayer.h

Index: Source/core/rendering/RenderLayer.h
diff --git a/Source/core/rendering/RenderLayer.h b/Source/core/rendering/RenderLayer.h
index 554a48e625f2986fff9be7d9584c3596948fb0e8..c6b9e25c02b2628ce34b85e99789b0965e5c5980 100644
--- a/Source/core/rendering/RenderLayer.h
+++ b/Source/core/rendering/RenderLayer.h
@@ -191,8 +191,7 @@ public:
     RenderLayer* enclosingPaginationLayer() const { return m_enclosingPaginationLayer; }
 
     void updateTransform();
-    void update3dRenderingContext();
-    RenderLayer* renderingContextRoot() const { return m_3dRenderingContextRoot; }
+    RenderLayer* renderingContextRoot();
 
     const LayoutSize& offsetForInFlowPosition() const { return m_offsetForInFlowPosition; }
 
@@ -337,7 +336,7 @@ public:
     bool has3DTransform() const { return m_transform && !m_transform->isAffine(); }
 
     // FIXME: reflections should force transform-style to be flat in the style: https://bugs.webkit.org/show_bug.cgi?id=106959
-    bool shouldFlattenTransform() const { return renderer()->hasReflection() || !renderer()->style() || renderer()->style()->transformStyle3D() != TransformStyle3DPreserve3D; }
+    bool shouldPreserve3D() const { return !renderer()->hasReflection() && renderer()->style()->transformStyle3D() == TransformStyle3DPreserve3D; }
 
     void filterNeedsRepaint();
     bool hasFilter() const { return renderer()->hasFilter(); }
@@ -744,10 +743,6 @@ private:
     // Pointer to the enclosing RenderLayer that caused us to be paginated. It is 0 if we are not paginated.
     RenderLayer* m_enclosingPaginationLayer;
 
-    // Pointer to the enclosing RenderLayer that establishes the 3d rendering context in which this layer participates.
-    // If it 0, it does not participate in a 3d rendering context.
-    RenderLayer* m_3dRenderingContextRoot;
-
     // Properties that are computed while updating compositing layers. These values may be dirty/invalid if
     // compositing status is not up-to-date before using them.
     struct CompositingProperties {