Direct composite canvas background if possible.

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 6823d005bb0d7c473c377887dc3236406aa5c52b..7ddbc9e736e232cb22a8eca8e4104a8af8a08ee3 100644
--- a/Source/core/testing/Internals.cpp
+++ b/Source/core/testing/Internals.cpp
@@ -1599,12 +1599,9 @@ String Internals::elementLayerTreeAsText(Element* element, unsigned flags, Excep
     }
 
     RenderLayer* layer = toRenderBox(renderer)->layer();
-    if (!layer) {
-        ec = InvalidAccessError;
-        return String();
-    }
-
-    if (!layer->backing() || !layer->backing()->graphicsLayer()) {
+    if (!layer
+        || !layer->backing()
+        || !layer->backing()->graphicsLayer()) {
         // Don't raise exception in these cases which may be normally used in tests.
         return String();
     }