I encountered the problem yesterday that `setTimeout(function(){})` return
`undefined` to me, which was supposed to be a number since it's a number in
JavaScript. For some cases, I need to use `clearTimeout` to manage some
delayed tasks.At first I was playing around on Android, it does not work. I tried iOS, failed too. By reading the code, it's just simply not implemented... it that right? https://github.com/apache/incubator-weex/blob/master/html5/shared/setTimeout.js#L24-L27 Any previous plan for setTimeout?
