GitLab

Add readPixels validation for RGBA / UNSIGNED_SHORT combination. This is
only valid with EXT_texture_norm16 extension enabled.

Bug: 1152259
Change-Id: I0e10b7d29f3b362c4054500270bbad87dcde599f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2559797
Commit-Queue: Shrek Shao <shrekshao@google.com>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#832141}