MANGLE the ANGLE Renderer class.

BUG=angle:789

Change-Id: Ib6d9d47a9353ea3c1a931b793baba85a2698b659
Reviewed-on: https://chromium-review.googlesource.com/225472
Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>