Should not repaint if a CSS property change can be composited

Source/core/rendering/RenderLayerModelObject.cpp

Index: Source/core/rendering/RenderLayerModelObject.cpp
diff --git a/Source/core/rendering/RenderLayerModelObject.cpp b/Source/core/rendering/RenderLayerModelObject.cpp
index 82b423b6d1e9e948e10fed043cf89f8d26c50929..d4514dd585bc64be0f932437e780dc5d72053e57 100644
--- a/Source/core/rendering/RenderLayerModelObject.cpp
+++ b/Source/core/rendering/RenderLayerModelObject.cpp
@@ -111,16 +111,19 @@ void RenderLayerModelObject::styleWillChange(StyleDifference diff, const RenderS
             // When a layout hint happens, we go ahead and do a repaint of the layer, since the layer could
             // end up being destroyed.
             if (hasLayer()) {
-                if (oldStyle->position() != newStyle->position()
-                    || oldStyle->zIndex() != newStyle->zIndex()
-                    || oldStyle->hasAutoZIndex() != newStyle->hasAutoZIndex()
-                    || !(oldStyle->clip() == newStyle->clip())
-                    || oldStyle->hasClip() != newStyle->hasClip()
-                    || oldStyle->opacity() != newStyle->opacity()
-                    || oldStyle->transform() != newStyle->transform()
-                    || oldStyle->filter() != newStyle->filter()
-                    )
-                layer()->repainter().repaintIncludingDescendants();
+                if (oldStyle->hasClip() != newStyle->hasClip()
+                    || oldStyle->clip() != newStyle->clip()) {
+                    // Composited layers don't need to be repainted when a parent's clip changes.
+                    layer()->repainter().repaintIncludingNonCompositingDescendants(this);
+                } else if (!layer()->hasCompositedLayerMapping()) {
+                    if (oldStyle->position() != newStyle->position()
+                        || oldStyle->zIndex() != newStyle->zIndex()
+                        || oldStyle->hasAutoZIndex() != newStyle->hasAutoZIndex()
+                        || oldStyle->opacity() != newStyle->opacity()
+                        || oldStyle->transform() != newStyle->transform()
+                        || oldStyle->filter() != newStyle->filter())
+                    layer()->repainter().repaintIncludingDescendants();
+                }
             } else if (newStyle->hasTransform() || newStyle->opacity() < 1 || newStyle->hasFilter()) {
                 // If we don't have a layer yet, but we are going to get one because of transform or opacity,
                 //  then we need to repaint the old position of the object.