When changing source files like Actions.jsm or scss / jsx in Phabricator, sometimes build assets are not updated, as well as the locale directory.

We should consider adding some kind of automated test that checks for missing changes / inconsistency; one option would be a more coarse-grained approach where if certain files change, the corresponding built file should be changed.

I'd like to prioritize this given a bunch of recent regressions.

Dan suggests:

• simple thing guaranteed to work, but has a lot of latency: add code at the beginning of try-runner.js to look at the date on bundle.js, then look at it after karma has run. if it's change, throw an error to make tree-herder go red

And if we're unhappy with the latency after doing that, we can tighten the feedback loop by fixing some already filed bugs:

2. make the builds not use shippable (read PGO) builds by fixing bug 1579162
3. then re-land bug 1567929 to run try-runner.js at code-review time
4. finally implement bug 1579154 to surface any issues into the front page of the review so it can't be missed

Dan, can you help take a look at this with Emily?

https://hg.mozilla.org/mozilla-central/rev/61c857bfd0fe