Fix unit test regressions from recent diff fragment changes.
Review Request #9228 — Created Sept. 28, 2017 and submitted — Latest diff uploaded
The recent changes to the JavaScript diff fragment rendering code
changed how state was stored and made collapsing an optional state.
That change neglected to update the unit tests accordingly for the new
storage and collapsible options, which this change fixes. It also
explicitly sets the expanded state for styling purposes, which wasn't
set before (and wasn't technically needed but might be needed down the
road).
Unit tests pass.
Tested diff fragments in expanded entries, collapsed entries, and in
the Review Dialog.