Causing failures on AMD OpenGL drivers for sRGB clears.

This reverts commit 04b89c97.

Change-Id: I51ee856d1c4d37882e5b1d1926415c398fa7ff5c
Reviewed-on: https://chromium-review.googlesource.com/301721Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>