Story 1457: Promote micro.tap to beta

Also, use tap events in editor, both for consistency and to ensure that
EL works (cancel event was bound to click, which would be prevented by
micro.tap).

Change-Id: I6dbe59796d2ab72a0747fe3bd7ae4162d07ce3c4
Hygiene: remove fallback for no header-loaded event

This was added in September in d5a36e4, it should be safe to remove it now.

Change-Id: I15e4cf43d47ddf8864003556be85496bf27f0e17
Merge "Story 1457: Promote micro.tap to beta"
Merge "Hygiene: remove fallback for no header-loaded event"