mediawiki.debug: Fix crash in browsers without Function#bind

PhantomJS has a partial ECMAScript 5 implementation but it does
not include Function.prototype.bind.  Detect that and error gracefully
instead of erroring out in the middle of a phantomjs qunit run.

Change-Id: Ic06e08490e8f297fda479c4adaf9b2d8735f63ad
Merge "mediawiki.debug: Fix crash in browsers without Function#bind"