Revert of Introduce SynchronousMutationObserver::didChangeAttribute()

third_party/WebKit/Source/core/dom/SynchronousMutationObserver.h

Index: third_party/WebKit/Source/core/dom/SynchronousMutationObserver.h
diff --git a/third_party/WebKit/Source/core/dom/SynchronousMutationObserver.h b/third_party/WebKit/Source/core/dom/SynchronousMutationObserver.h
index 8d4d17fbafd75f0e96d231b848bfbaee65ce5c0b..ad0311ca64c0168fee3532f37ab0ec9647d59f5a 100644
--- a/third_party/WebKit/Source/core/dom/SynchronousMutationObserver.h
+++ b/third_party/WebKit/Source/core/dom/SynchronousMutationObserver.h
@@ -14,7 +14,6 @@
 class CharacterData;
 class ContainerNode;
 class Document;
-class Element;
 class NodeWithIndex;
 class Text;
 
@@ -40,9 +39,6 @@
   //  - didMoveTreeToNewDocument(const Node& root);
   //  - didInsertText(Node*, unsigned offset, unsigned length);
   //  - didRemoveText(Node*, unsigned offset, unsigned length);
-
-  // Called just after attribute is changed.
-  virtual void didChangeAttribute(const Element&);
 
   // Called after child nodes changed.
   virtual void didChangeChildren(const ContainerNode&);