Remove outdated ObjC-related comments from the IDL

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 722419705919c084343430276033b3375b187075..df1d7dfd1bee8690eaf90e08ea1891f8c658ee8b 100644
--- a/Source/core/dom/Element.idl
+++ b/Source/core/dom/Element.idl
@@ -35,7 +35,6 @@
     [RaisesException, CustomElementCallbacks=Enable, MeasureAs=ElementRemoveAttributeNode] Attr removeAttributeNode([Default=Undefined, StrictTypeChecking] optional Attr oldAttr); // Removed from DOM4.
     [PerWorldBindings] NodeList getElementsByTagName([Default=Undefined] optional DOMString name);
 
-    // For ObjC this is defined on Node for legacy support.
     [PerWorldBindings] readonly attribute NamedNodeMap     attributes;
     boolean            hasAttributes();