Fix uninitialized stencil ref variables in the GL backend BUG=angleproject:1443 Change-Id: I8c259368abdffb57c2963b29f81e2433a08ecae1 Reviewed-on: https://chromium-review.googlesource.com/360110 Reviewed-by: Geoff Lang <geofflang@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>