Don't call RenderObject::enclosingLayer on a null pointer

Source/core/page/scrolling/ScrollingCoordinator.cpp

Index: Source/core/page/scrolling/ScrollingCoordinator.cpp
diff --git a/Source/core/page/scrolling/ScrollingCoordinator.cpp b/Source/core/page/scrolling/ScrollingCoordinator.cpp
index fb14b239c7a793aaa14b2e3d25578b73a064dfdc..bca52a84bda83b20e2a3c48346c4d952c8b71a8d 100644
--- a/Source/core/page/scrolling/ScrollingCoordinator.cpp
+++ b/Source/core/page/scrolling/ScrollingCoordinator.cpp
@@ -394,7 +394,8 @@ static void makeLayerChildFrameMap(const LocalFrame* currentFrame, LayerFrameMap
     map->clear();
     const FrameTree& tree = currentFrame->tree();
     for (const LocalFrame* child = tree.firstChild(); child; child = child->tree().nextSibling()) {
-        if (const RenderLayer* containingLayer = child->ownerRenderer()->enclosingLayer()) {
+        if (const RenderObject* ownerRenderer = child->ownerRenderer()) {

[esprehn, 2014/03/27 23:54:28]

Might be nicer to use a "continue" instead of nesting the whole loop.

+            const RenderLayer* containingLayer = ownerRenderer->enclosingLayer();
             LayerFrameMap::iterator iter = map->find(containingLayer);
             if (iter == map->end())
                 map->add(containingLayer, Vector<const LocalFrame*>()).storedValue->value.append(child);