Passes all ETC1 related dEQP tests on Windows.

BUG=angleproject:1212
TEST=dEQP-GLES2.capability.extensions.compressed_texture_formats.GL_OES_compressed_ETC1_RGB8_texture
TEST=dEQP-GLES2.functional.texture.format.*
TEST=dEQP-GLES2.functional.texture.wrap.*
TEST=dEQP-GLES2.functional.texture.filtering.*
TEST=dEQP-GLES3.functional.texture.format.compressed.etc1*
TEST=dEQP-GLES3.functional.texture.filtering.*

Change-Id: I937b039f90161bb5e8777766ea0c032ddfbbf159
Reviewed-on: https://chromium-review.googlesource.com/312416Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tryjob-Request: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Minmin Gong <mgong@microsoft.com>