Review Request #9356 - Created Nov. 9, 2017 and submitted
This fixes one serious bug (in some browsers) where a missing variable
breaking the Update -> Update Diff action. While I was fixing that up, I
decided to fix up the other things that jshint complained about.
- Verified that Update -> Update Diff now worked as expected in strict
- Ran jshint.
- Ran js-tests.