executeScript method
执行指定脚本语句;script为脚本语句
Implementation
@override
Future<dynamic> executeScript(String pageName, String script) {
var map = <dynamic, dynamic>{};
map[FairMessage.LOAD_JS] = script;
var msg = FairMessage(pageName, FairMessage.EVALUATE, map);
var from = msg.from();
var reply = _channel!.sendCommonMessageSync(jsonEncode(from));
return Future.value(reply);
}