Add a test case for enabled-but-inactive vertex attributes
Add a test case for enabled-but-inactive vertex attributes

Bug: angleproject:2138

Change-Id: Ia5331845d34f60a31280e6da041d13dc3da29232
Reviewed-on: https://chromium-review.googlesource.com/1187364
Commit-Queue: Shahbaz Youssefi <582eeec4f08a2ccd61e3ef52115e6e7c571582de@chromium.org>
Reviewed-by: Geoff Lang <b6fc25fe0362055230985c05cbfa8adb741ccc0f@chromium.org>

ppy/angle,ppy/angle,ppy/angle,ppy/angle