Opening about:support on Windows results in WebGL related errors

Opening about:support on Windows results in the following output in the browser console:

Error: WebGL warning: Unable to restrict WebGL limits to minimums. Troubleshoot.jsm:525:18
Error: WebGL warning: Failed to create WebGL context: WebGL creation failed:
* Troubleshoot.jsm:525:18

The suggestion is that ANGLE is broken. (Reported in our blog: https://blog.torproject.org/comment/275959#comment-275959).