After this change, the SimpleTexture2D sample mostly runs.

BUG=angleproject:2167

Change-Id: Ie6d56f890b1aede329e11d1e987d0f8c17a2d0b4
Reviewed-on: https://chromium-review.googlesource.com/720072Reviewed-by: Frank Henigman <fjhenigman@chromium.org>