UniformTest.SamplerUniformsAppearOnce should check for VTF support Change-Id: If4b1602a5f706b5343fc1757962341602354b88e Reviewed-on: https://chromium-review.googlesource.com/304389 Reviewed-by: Geoff Lang <geofflang@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Tryjob-Request: Jamie Madill <jmadill@chromium.org> Tested-by: Austin Kinross <aukinros@microsoft.com>