Steps to Reproduce

current implementation will stop a comet request when the request is aborted by a browser.

Current Result

zkex.cmsp.SPush = zk.$extends(zk.Object, {
...
    _send: function () {
		...
			req.onabort = this.proxy(this.stop);

Expected Result

retry when it's aborted

Debug Info

• possible reasons that Chrome aborts a request: https://stackoverflow.com/a/13459106/1281378
• the user doesn't know the reason of abortion yet, we can research more before implementing it
• the user confirms that retry after abort solve their problem, even he still don't know the reason of abortion.