Use Traversal<HTMLSourceElement> to find the next source candidate

Source/core/html/HTMLMediaElement.h

Index: Source/core/html/HTMLMediaElement.h
diff --git a/Source/core/html/HTMLMediaElement.h b/Source/core/html/HTMLMediaElement.h
index 5b2756e307c7194f13580ffbab0eaf47f58488ee..68865aa354665992921fcec9dba5f6e5cf6394e0 100644
--- a/Source/core/html/HTMLMediaElement.h
+++ b/Source/core/html/HTMLMediaElement.h
@@ -499,8 +499,8 @@ private:
     // Loading state.
     enum LoadState { WaitingForSource, LoadingFromSrcAttr, LoadingFromSourceElement };
     LoadState m_loadState;
-    RefPtrWillBeMember<HTMLSourceElement> m_currentSourceNode;
-    RefPtrWillBeMember<Node> m_nextChildNodeToConsider;
+    RefPtrWillBeMember<HTMLSourceElement> m_currentSourceElement;
+    RefPtrWillBeMember<HTMLSourceElement> m_nextSourceElement;
 
     // "Deferred loading" state (for preload=none).
     enum DeferredLoadState {