Simply rules for compositing fixed position elements

Source/core/rendering/compositing/RenderLayerCompositor.h

Index: Source/core/rendering/compositing/RenderLayerCompositor.h
diff --git a/Source/core/rendering/compositing/RenderLayerCompositor.h b/Source/core/rendering/compositing/RenderLayerCompositor.h
index feec79c6d13b8d57f1ad2c3c09da4bb6c4f5a976..edf4f5858285fa880377e8ffefdc9030797192df 100644
--- a/Source/core/rendering/compositing/RenderLayerCompositor.h
+++ b/Source/core/rendering/compositing/RenderLayerCompositor.h
@@ -179,10 +179,6 @@ private:
     void assertNoUnresolvedDirtyBits();
 #endif
 
-    // Make updates to the layer based on viewport-constrained properties such as position:fixed. This can in turn affect
-    // compositing.
-    bool updateLayerIfViewportConstrained(RenderLayer*);
-
     // GraphicsLayerClient implementation
     virtual void notifyAnimationStarted(const GraphicsLayer*, double) OVERRIDE { }
     virtual void paintContents(const GraphicsLayer*, GraphicsContext&, GraphicsLayerPaintingPhase, const IntRect&) OVERRIDE;