The fields renderTargetFormat and depthStencilFormat are now required.

BUG=none

Change-Id: I8dff771fc8c28b297bc7d47f9aef7f78ba0f3f86
Reviewed-on: https://chromium-review.googlesource.com/443804Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Frank Henigman <fjhenigman@chromium.org>