Bug 456284 - JSExtendedClass requires an equality hook. r=crowder, a191=beltzner.

js/src/jsobj.cpp

@@ -2591,6 +2591,10 @@ js_NewObjectWithGivenProto(JSContext *cx, JSClass *clasp, JSObject *proto,
         objectSize = sizeof(JSObject);
     }
 
+    /* Assert that the class is a proper class. */
+    JS_ASSERT_IF(clasp->flags & JSCLASS_IS_EXTENDED,
+                 ((JSExtendedClass *)clasp)->equality);
+
     /*
      * Allocate an object from the GC heap and initialize all its fields before
      * doing any operation that can potentially trigger GC.