Prune switch(constant) with no matching case Bug: chromium:350528343 Change-Id: Iabb475b230f22086de482bbdcf2fa00b0d986622 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5735815 Auto-Submit: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Geoff Lang <geofflang@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>