Only update composited scrolling state when necessary

Source/core/rendering/RenderLayerCompositor.cpp

Index: Source/core/rendering/RenderLayerCompositor.cpp
diff --git a/Source/core/rendering/RenderLayerCompositor.cpp b/Source/core/rendering/RenderLayerCompositor.cpp
index 8cb4aac64005a362029e4f29377bb389b837583c..397a5e8703c6d3b0c683f0d2c716caeb5eebb490 100644
--- a/Source/core/rendering/RenderLayerCompositor.cpp
+++ b/Source/core/rendering/RenderLayerCompositor.cpp
@@ -2590,7 +2590,7 @@ static bool isRootmostFixedOrStickyLayer(RenderLayer* layer)
     if (layer->renderer()->style()->position() != FixedPosition)
         return false;
 
-    for (RenderLayer* stackingContainer = layer->stackingContainer(); stackingContainer; stackingContainer = stackingContainer->stackingContainer()) {
+    for (RenderLayer* stackingContainer = layer->ancestorStackingContainer(); stackingContainer; stackingContainer = stackingContainer->ancestorStackingContainer()) {
         if (stackingContainer->isComposited() && stackingContainer->renderer()->style()->position() == FixedPosition)
             return false;
     }