This change fixes a bunch of broken js-tests, but it came down to three

problems:

The FileAttachmentThumbnailView was checking the newly-added

canAccessReviewUI attribute, but that wasn't set in the test that

  needed it. While I was doing this I fixed up the type in the

  attributes definition.
The check for the tab_size field was assuming that we had a file

  set on the reviewable, which many unit tests did not do. I've changed

  the implementation to check for that instead of assuming.
Similarly, the check to allow self ship-it was assuming that there was

  a "submitter" link present on the review request, when many unit tests

  did not set that data. I've changed it to check existence first.

Ran js-tests.