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. Testing Done: Ran js-tests.