This function is no longer used.

Bug: b/172704839
Change-Id: I649b205aa5603a25ed28a5fae12ad455d02d0145
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2537236
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com>
Reviewed-by: Tim Van Patten <timvp@google.com>