Back out patch for bug 469625, it mysterious busts stuff.

js/src/jsarray.cpp

@@ -831,6 +831,8 @@ array_defineProperty(JSContext *cx, JSObject *obj, jsid id, jsval value,
     if (!isIndex || attrs != JSPROP_ENUMERATE) {
         if (!ENSURE_SLOW_ARRAY(cx, obj))
             return JS_FALSE;
+        if (isIndex && STOBJ_IS_DELEGATE(obj))
+            cx->runtime->anyArrayProtoHasElement = JS_TRUE;
         return js_DefineProperty(cx, obj, id, value, getter, setter, attrs, propp);
     }