IEMobile/9.0 undefines .responseText during readyState == 3: is any streaming possible?
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I am trying to build a service that uses a variation of a long poll to send results back to a Windows Phone 7 "Mango" device where initial results come back quickly and as the server calculates better results they are sent over the same response.

The phone has the `Mozilla/5.0 (compatible; MSIE 9.0; Windows Phone OS 7.5; Trident/5.0; IEMobile/9.0; NOKIA; Lumia 800)` browser. I can see that IEMobile/9.0 enters `readyState == 3`, but any attempt to read the `.responseText` results in an `Error: The data necessary to complete this operation is not yet available.` During this time `readyState == 3` the `.responseXML` is null.

Some investigations show that question [IE7/8 responseText in readyState 3 not available][1] still applies, but I was hoping that IEMobile/9 might offer new work-arounds. 

I have tried some different server Content-Types (`application/json`, `application/json-stream`, `application/octet-stream`) but to no avail.

So my question is whether there is any way of reading a stream's partial content in a single request using IEMobile/9.0? As the entire lifetime of the "results" is only 5 or so seconds and as it's intende to work over mobile phone networks, I would prefer to avoid having to fake out on the server-side an AJAX handler and make repeated requests from the phone.

(ps: if someone could create a new tag "IEMobile/9.0" and add it I'd appreciate it ...)

  [1]: http://stackoverflow.com/questions/4158435/ie7-8-responsetext-in-readystate-3-not-available