In order to speed up file list processing for large numbers of files,
event handlers have been removed on a per-line basis and instead
are listened for in a parent container that handles them according to
the click target.
With a sample of 1300 files, the dom-repeat after clicking 'show all'
gets rendered 25% faster.
Bug: Issue 5612
Change-Id: Idc1ba6e0810d5d4c6f36e76667c3748becc1358a