Much of the infrastructure to run "self test" tests (those which test
core functionality of the `meteor` tool itself) in PhantomJS and
BrowserStack was already in place, though the BrowserStack portion had
been disabled some time ago, though the exact reason isn't entirely
clear.
BrowserStack could play an important roll in Meteor's future as Meteor
works to ensure that the bundle delivered to the client is appropriate
for that client's capabilities, including appropriate polyfills to
implement functionality not natively available in the browser (e.g.
ECMAScript features, SockJS, etc.).
The single file which represented the bulk of the `meteor self-test`
functionality had got a bit heavy and it stood to benefit from some
dissemination.
I embarked on this change originally when looking into replacing
PhantomJS with Chrome Headless (and a new `ChromeClient` class) within
self-test. Unfortunately, I didn't have time to take this the last
step of actually implementing Chrome, but this should hopefully
facilitate that change in the future by providing what I believe to be
better compartmentalization of this logic.
I apologize for the (likely) difficulty of reviewing this commit. Due
to heavy intertwining of existing code it was hard to arrange these
changes in an easy-to-review manner. I believe a reviewer will
find that it's mainly copy and pasting into different files and
careful adjusting of those files (new) module dependencies.
