Expand collapse diffs spec fails locally but not on CI

As I was going through a refactor today, I ran across rspec ./spec/features/expand_collapse_diffs_spec.rb; that fails locally and passes on CI. This occurred when I ran this test against master locally. My latest master already has the webpack helper fix, so I'm confused as to why this spec isn't working (especially since it doesn't seem to touch the IDE code).

I also had @jivanvl run this test locally and he too had errors on that rspec.