ANGLE uses a workflow where we upload stacks of dependent patches to
Gerrit. The Chromium workflow has squashed by default for a long time,
so the infra team is planning to switch to squash by default. This
change will preserve our workflow.

See http://crbug.com/611892

BUG=None

Change-Id: I62ab7a26d5bd899fbb8c48a1aced7d044640a66a
Reviewed-on: https://chromium-review.googlesource.com/353039Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>