SPIR-V switch statement support

Bug: skia:
Change-Id: I0e44b103820745614c29ff08ab100d46abd3a0de
Reviewed-on: https://skia-review.googlesource.com/70960
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
2 files changed