For some reason we were using the second GLint value passed into the
method, when the spec says we should have a single clear value.

Noticed when adding tests for lazy robust resource init (tests will
be added in a subsequent patch).

BUG=angleproject:2107

Change-Id: Iadfc5072796255072bfb71ff1918253045e29576
Reviewed-on: https://chromium-review.googlesource.com/675049
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Frank Henigman <fjhenigman@chromium.org>