Implement Custom Elements' attributeChangedCallback.

Source/core/dom/Element.idl

Index: Source/core/dom/Element.idl
diff --git a/Source/core/dom/Element.idl b/Source/core/dom/Element.idl
index 543a8a17f61daabc62c2db868b13fc2b9338242b..d7a7a69351c037bb08a71c21fe65a5561991ac16 100644
--- a/Source/core/dom/Element.idl
+++ b/Source/core/dom/Element.idl
@@ -27,12 +27,12 @@
     [TreatReturnedNullStringAs=Null, PerWorldBindings] readonly attribute DOMString tagName;
 
     [TreatReturnedNullStringAs=Null] DOMString getAttribute([Default=Undefined] optional DOMString name);
-    [RaisesException] void setAttribute([Default=Undefined] optional DOMString name,
+    [RaisesException, DeliverCustomElementCallbacks] void setAttribute([Default=Undefined] optional DOMString name,
                                      [Default=Undefined] optional DOMString value);
-    void removeAttribute([Default=Undefined] optional DOMString name);
+    [DeliverCustomElementCallbacks] void removeAttribute([Default=Undefined] optional DOMString name);
     Attr getAttributeNode([Default=Undefined] optional DOMString name);
-    [RaisesException] Attr setAttributeNode([Default=Undefined, StrictTypeChecking] optional Attr newAttr);
-    [RaisesException] Attr removeAttributeNode([Default=Undefined, StrictTypeChecking] optional Attr oldAttr);
+    [RaisesException, DeliverCustomElementCallbacks] Attr setAttributeNode([Default=Undefined, StrictTypeChecking] optional Attr newAttr);
+    [RaisesException, DeliverCustomElementCallbacks] Attr removeAttributeNode([Default=Undefined, StrictTypeChecking] optional Attr oldAttr);
     [PerWorldBindings] NodeList getElementsByTagName([Default=Undefined] optional DOMString name);
 
     // For ObjC this is defined on Node for legacy support.
@@ -43,10 +43,10 @@
 
      DOMString getAttributeNS([TreatNullAs=NullString,Default=Undefined] optional DOMString namespaceURI,
                                             [Default=Undefined] optional DOMString localName);
-     [RaisesException] void setAttributeNS([TreatNullAs=NullString,Default=Undefined] optional DOMString namespaceURI,
+     [RaisesException, DeliverCustomElementCallbacks] void setAttributeNS([TreatNullAs=NullString,Default=Undefined] optional DOMString namespaceURI,
                                        [Default=Undefined] optional DOMString qualifiedName,
                                        [Default=Undefined] optional DOMString value);
-     void removeAttributeNS([TreatNullAs=NullString] DOMString namespaceURI,
+     [DeliverCustomElementCallbacks] void removeAttributeNS([TreatNullAs=NullString] DOMString namespaceURI,
                                           DOMString localName);
      NodeList getElementsByTagNameNS([TreatNullAs=NullString,Default=Undefined] optional DOMString namespaceURI,
                                                    [Default=Undefined] optional DOMString localName);