Re-enable the flaky test InitUninitializedStructContainingArrays that
was failing because of this option missing.

Bug: angleproject:2460
Change-Id: Icf794a5fdca48619756d575faa4cb04f0323712e
Reviewed-on: https://chromium-review.googlesource.com/1014271
Commit-Queue: Luc Ferron <lucferron@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>