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

Source/core/html/MediaDocument.cpp

Index: Source/core/html/MediaDocument.cpp
diff --git a/Source/core/html/MediaDocument.cpp b/Source/core/html/MediaDocument.cpp
index 14d8d99c67c44f59da767fd43a1a4e91a0c46108..ed214bab0cfa62befd4fca3c34caaf2c091cd972 100644
--- a/Source/core/html/MediaDocument.cpp
+++ b/Source/core/html/MediaDocument.cpp
@@ -134,7 +134,7 @@ static inline HTMLVideoElement* descendentVideoElement(Node* root)
 {
     ASSERT(root);
 
-    for (Node* node = root; node; node = NodeTraversal::next(node, root)) {
+    for (Node* node = root; node; node = NodeTraversal::next(*node, root)) {
         if (isHTMLVideoElement(node))
             return toHTMLVideoElement(node);
     }