refactor: mark weex-specific block

Author: yyx990803

src/core/vdom/helpers/update-listeners.js

@@ -54,7 +54,8 @@ export function updateListeners (
     def = cur = on[name]
     old = oldOn[name]
     event = normalizeEvent(name)
-    if (isPlainObject(def)) {
+    // $flow-disable-line
+    if (__WEEX__ && isPlainObject(def)) {
       cur = def.handler
       event.params = def.params
     }