fix(JSInterface): 修复 API Level 17 及以上无法正确调用本地 JS 接口的 bug

JELLY_BEAN_MR1 即 API Level 17 以上，必须使用 JavascriptInterface 注解 public 方法，才能被 Javascript 调用。

### Android 文档中有提及：

> Injects the supplied Java object into this WebView. The object is injected into the JavaScript context of the main frame, using the supplied name. This allows the Java object's methods to be accessed from JavaScript. For applications targeted to API level JELLY_BEAN_MR1 and above, only public methods that are annotated with JavascriptInterface can be accessed from JavaScript. For applications targeted to API level JELLY_BEAN or below, all public methods (including the inherited ones) can be accessed, see the important security note below for implications.