It seems that a number of the tests had started failing when run in
Chrome. They were fine under PhantomJS, but the MegolmExport tests only work
under Chrome, and I need them to work...
Mostly the problems were timing-related, where assumptions made about how
quickly the `then` handler on a promise would be called were no longer
valid. Possibly Chrome 55 has made some changes to the relative priorities of
setTimeout and sendMessage calls.
One of the TimelinePanel tests was failing because it was expecting the contents
of a div to take up more room than they actually were. It's possible this is
something very environment-specific; hopefully the new value will work on a
wider range of machines.
Also some logging tweaks.
Under certain conditions, it was possible to get stuck in a state where any
user-initiated scroll would be met with "Working around
vector-im/vector-web#528" and overridden. Fix this by removing the duplication
between _lastSetScroll and recentEventScroll, and using _lastSetScroll which is
more reliable.
It does something, but things I don't like:
* it churns for 15 seconds webpacking everything. Do we really need to get
webpack involved here?
* I don't think there's any way to control which tests get run and which don't.
Other things I'd want to fix up include:
* Make it run on jsdom or phantomjs instead of Chrome
* figure out how to configure babel without a .babelrc
