out-of-bounds-uniform-array-access.html could fail on Linux Nvidia
OpenGL even if GL_KHR_robust_buffer_access_behavior is available.
Turning clampArrayAccess on globally but turn it off for Compute Shader,
which is not used by WebGL so should be okay.

FYI: The failures when turning this on globally are all in compute shaders.
One could be fixed by using int cast instead of float for the clamp
modifier. The other is due to array.length() couldn't return correct
result for array in SSBO.

Bug: chromium:1042252
Change-Id: Ic6f7adae4600d35207646881b18990a0c25a889a
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2020463
Commit-Queue: Shrek Shao <shrekshao@google.com>
Reviewed-by: Kenneth Russell <kbr@chromium.org>