GLES1: Use less precision for color and tex coords Per the GLES1 spec, color and tex coords are satisified by half-precision floats. Bug: angleproject:6644 Change-Id: Ia3f8e45d4c35557a25373f9ad572e87708bc2001 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4067803 Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Cody Northrop <cnorthrop@google.com>