During the development of the change to include css_media and js_media in the data for the files in the diff viewer for binary files which use review UIs, these keys got moved from the diffviewer code into reviews, which creates its own list of files. The file list created by the reviews code goes into a separate key in the context, and the unit test for these wasn't updated, causing the test to fail. This change fixes that. Testing Done: Ran unit tests.