We won't always find the prototype property, especially if our __proto__ has been cut off. bug 327608, r=brendan

js/src/jsfun.c

@@ -1043,7 +1043,7 @@ fun_enumerate(JSContext *cx, JSObject *obj)
     prototypeId = ATOM_TO_JSID(cx->runtime->atomState.classPrototypeAtom);
     if (!OBJ_LOOKUP_PROPERTY(cx, obj, prototypeId, &pobj, &prop))
         return JS_FALSE;
-    JS_ASSERT(prop);
+    if (prop)
         OBJ_DROP_PROPERTY(cx, pobj, prop);
     return JS_TRUE;
 }