In GLSL, all identifiers beginning with gl_ are reserved (not just those
explicitly named in the spec), and so any found in WGSL must be renamed.
Bug: tint:1304
Change-Id: I92ed7ec674620f67775378ecb8debcfdb4b5bbb4
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/69701
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>