Fix & clarify some comments in compositing. Rename clippedByAncestor to more accurately

Source/core/rendering/compositing/RenderLayerCompositor.cpp

Index: Source/core/rendering/compositing/RenderLayerCompositor.cpp
diff --git a/Source/core/rendering/compositing/RenderLayerCompositor.cpp b/Source/core/rendering/compositing/RenderLayerCompositor.cpp
index 01a04748d83e442d29fd2b80fd91d52e69057ff1..74e252aa3006ce2802e821f669ae254a8d0a53ae 100644
--- a/Source/core/rendering/compositing/RenderLayerCompositor.cpp
+++ b/Source/core/rendering/compositing/RenderLayerCompositor.cpp
@@ -1209,7 +1209,7 @@ bool RenderLayerCompositor::canBeComposited(const RenderLayer* layer) const
 // according to the z-order hierarchy, yet clipping goes down the renderer hierarchy.
 // Thus, a RenderLayer can be clipped by a RenderLayer that is an ancestor in the renderer hierarchy,
 // but a sibling in the z-order hierarchy.
-bool RenderLayerCompositor::clippedByAncestor(const RenderLayer* layer) const
+bool RenderLayerCompositor::clippedByNonAncestorInStackingTree(const RenderLayer* layer) const
 {
     if (!layer->hasCompositedLayerMapping() || !layer->parent())
         return false;