XR Test Refactor Part 3.3: Miscellaneous Cleanup

Collection of miscellaneous code cleanup changes:
1. Add uses of assertNoJavaScriptErrors where applicable
2. Add missing JavaDoc comments and standardize format (aversion to
   periods fixed)
3. Convert some uses of AtomicReference<Integer> to AtomicInteger
4. Remove @RetryOnFailure since automatic retries were re-added a
   while back, making them unnecessary

Bug: 863256
Change-Id: I568ea12983cec661874dbfb365d1c1a7e06f6b6d
Reviewed-on: https://chromium-review.googlesource.com/1145766
Commit-Queue: Brian Sheedy <bsheedy@chromium.org>
Reviewed-by: Amirhossein Simjour <asimjour@chromium.org>
Cr-Commit-Position: refs/heads/master@{#578024}
27 files changed