Don't coerce pointers to compositor layer mappings to booleans.

Source/core/testing/Internals.cpp

Index: Source/core/testing/Internals.cpp
diff --git a/Source/core/testing/Internals.cpp b/Source/core/testing/Internals.cpp
index 5cacf1c22cefcf96bf49b194a38d93b2f97319c2..0a6dff2ad5403dc64c0f0576f93ff8fd4e1c424c 100644
--- a/Source/core/testing/Internals.cpp
+++ b/Source/core/testing/Internals.cpp
@@ -1257,7 +1257,9 @@ unsigned Internals::touchEventHandlerCount(Document* document, ExceptionState& e
 
 static RenderLayer* findRenderLayerForGraphicsLayer(RenderLayer* searchRoot, GraphicsLayer* graphicsLayer, String* layerType)
 {
-    if (searchRoot->compositedLayerMapping() && graphicsLayer == searchRoot->compositedLayerMapping()->mainGraphicsLayer())
+    // Note, we only want to return the RenderLayer that _truly_ owns the GraphicsLayer, not just the
+    // first RenderLayer we encounter that paints into it.
+    if (searchRoot->compositingState() == PaintsIntoOwnBacking && graphicsLayer == searchRoot->compositedLayerMapping()->mainGraphicsLayer())
         return searchRoot;
 
     GraphicsLayer* layerForScrolling = searchRoot->scrollableArea() ? searchRoot->scrollableArea()->layerForScrolling() : 0;
@@ -1740,7 +1742,7 @@ String Internals::elementLayerTreeAsText(Element* element, unsigned flags, Excep
 
     RenderLayer* layer = toRenderBox(renderer)->layer();
     if (!layer
-        || !layer->compositedLayerMapping()
+        || !layer->hasCompositedLayerMapping()
         || !layer->compositedLayerMapping()->mainGraphicsLayer()) {
         // Don't raise exception in these cases which may be normally used in tests.
         return String();