Have ElementTraversal / NodeTraversal's next() methods take a reference

Source/bindings/v8/V8GCController.cpp

Index: Source/bindings/v8/V8GCController.cpp
diff --git a/Source/bindings/v8/V8GCController.cpp b/Source/bindings/v8/V8GCController.cpp
index 23b00b4d20db69379835ee9e5ae93cc0230f1217..271427fcf589377bfedd3902c91766ea937d1b70 100644
--- a/Source/bindings/v8/V8GCController.cpp
+++ b/Source/bindings/v8/V8GCController.cpp
@@ -157,7 +157,7 @@ private:
         // To make each minor GC time bounded, we might need to give up
         // traversing at some point for a large DOM tree. That being said,
         // I could not observe the need even in pathological test cases.
-        for (Node* node = rootNode; node; node = NodeTraversal::next(node)) {
+        for (Node* node = rootNode; node; node = NodeTraversal::next(*node)) {
             if (node->containsWrapper()) {
                 // FIXME: Remove the special handling for image elements.
                 // The same special handling is in V8GCController::opaqueRootForGC().