addJavaScriptHandler do not work well in Android Api <= 22

[DreamBuddy]

Because addJavaScriptHandler use the 'Promise', but Android Webview does not support until api level 23.

I think,When the webview didn't support it ,We can make our 'MyPromise' or try other ways

[DreamBuddy]

private static final String MyPromise = "class MyPromise{constructor(e){if(this.resolveQueue=[],this.rejectQueue=[],this.message=null,this._status='PENDING','function'!=typeof e)throw Error('MyPromise 必须传递一个解析函数');try{e(this._resolve.bind(this),this._reject.bind(this))}catch(e){this._reject(e)}}_resolve(e){return'PENDING'!==this._status?this:(this.message=e,this._status='RESOLVED',this.resolveQueue.forEach(e=>{this._excute(e)}),this)}_reject(e){return'PENDING'!==this._status?this:(this.message=e,this._status='REJECTED',this.rejectQueue.forEach(e=>{this._excute(e)}),this)}then(e,t){let s=this._status;return'RESOLVED'===s&&this._excute(e),'REJECTED'===s&&this._excute(t),'PENDING'===s&&(this.resolveQueue.push(e),this.rejectQueue.push(t)),this}_excute(e){if(this._callback=e||function(){},'undefined'!=typeof MutationObserver){this.targetNode=document.createElement('i'),this.targetNode.id='INITIAL';let e={attributes:!0};return new MutationObserver(e=>{for(let t of e)'attributes'===t.type&&this._callback(this.message)}).observe(this.targetNode,e),void(this.targetNode.id=this._status)}if(process)process.nextTick(e=>{this._callback(this.message)});else{if('undefined'!=typeof MessageChannel){let e=new MessageChannel,t=e.port1,s=e.port2;return t.postMessage({}),void s.onmessage(e=>{this._callback(this.message)})}setTimeout(e=>{this._callback(this.message)},0)}}}";

  public static final String flutterInAppBroserJSClass = MyPromise + "window." + name + ".callHandler = function() {"
      + "var _callHandlerID = setTimeout(function(){});" + "window." + name
      + "._callHandler(arguments[0], _callHandlerID, JSON.stringify(Array.prototype.slice.call(arguments, 1)));"
      + "var _MyPromise = typeof Promise !== 'undefined'?Promise:MyPromise;" + "return new _MyPromise(function(resolve, reject) {" + "  window."
      + name + "[_callHandlerID] = resolve;" + "});" + "}";