Add Object::IsDirty function in the API.

include/v8.h

Index: include/v8.h
===================================================================
--- include/v8.h	(revision 2910)
+++ include/v8.h	(working copy)
@@ -1238,6 +1238,15 @@
   bool SetHiddenValue(Handle<String> key, Handle<Value> value);
   Local<Value> GetHiddenValue(Handle<String> key);
   bool DeleteHiddenValue(Handle<String> key);
+  
+  /**
+   * Returns true if this is an instance of an api function (one
+   * created from a function created from a function template) and has
+   * been modified since it was created.  Note that this method is
+   * conservative and may return true for objects that haven't actually
+   * been modified.
+   */
+  bool IsDirty();
 
   /**
    * Clone this object with a fast but shallow copy.  Values will point