Always give RenderParts a RenderLayer.

Source/core/rendering/RenderBox.cpp

Index: Source/core/rendering/RenderBox.cpp
diff --git a/Source/core/rendering/RenderBox.cpp b/Source/core/rendering/RenderBox.cpp
index 64c7940701b19e88212a87e2aa0ec91efa891f6f..3aebe00641827634397db06e5117e4903d7ad023 100644
--- a/Source/core/rendering/RenderBox.cpp
+++ b/Source/core/rendering/RenderBox.cpp
@@ -1073,7 +1073,7 @@ bool RenderBox::nodeAtPoint(const HitTestRequest& request, HitTestResult& result
 
     // Check kids first.
     for (RenderObject* child = slowLastChild(); child; child = child->previousSibling()) {
-        if (!child->hasLayer() && child->nodeAtPoint(request, result, locationInContainer, adjustedLocation, action)) {
+        if ((!child->hasLayer() || !toRenderLayerModelObject(child)->layer()->isSelfPaintingLayer()) && child->nodeAtPoint(request, result, locationInContainer, adjustedLocation, action)) {
             updateHitTestResult(result, locationInContainer.point() - toLayoutSize(adjustedLocation));
             return true;
         }