Add tests for switch + loop constructs.

Change-Id: I17b5e21a28140b8e9313d87af9b1145674214fdb
Bug: skia:12450
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/450989
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
6 files changed