[QA] Running VisualEditor browsertests via Vagrant VM

[Jeff Hall]

I noticed that in order to successfully run browser tests in the 
"VisualEditor" repo via the Vagrant virtual machine package, a couple of 
specific extra steps were needed that differ from the procedure used for 
running tests in the "browsertests" repo.  I added notes here:

https://www.mediawiki.org/wiki/Quality_Assurance/Browser_testing/Running_and_writing_tests#Running_VisualEditor_browser_tests_via_Vagrant

If that's not the best page to include that information, let me know and 
I'd be happy to re-locate it, but I figure this info is worth capturing 
somewhere!

Cheers,

Jeff