Update stream.js - Bugfix

https://bugzilla.mozilla.org/show_bug.cgi?id=956328
https://developer.mozilla.org/en-US/docs/XPCOM_Interface_Reference/NsIRequest#isPending%28%29

Prevent NS_ERROR_UNEXPECTED exception from being thrown if the nsIRequest instance isn't paused when the resume method is called.
Merge pull request #1339 from DecipherCode/master

Bug 956328 Stream.resume triggers a resume on an unpaused stream pump r=@gozala