So ANGLE's Ozone backend gets compiled.

BUG=angleproject:1412

Change-Id: Id4b401f59cd9d3f4dd0b945af67ecc0c9e5d68a2
Reviewed-on: https://chromium-review.googlesource.com/395607
Commit-Queue: Frank Henigman <fjhenigman@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>