Add support for inlining switches with returns inside.

Because we use `continue` for flow control handling now, we can escape
from the middle of a switch statement. This wasn't possible when we used
`break`.

This unlocks some pretty stellar optimization opportunities if the
switch value can be determined at compile time; see BlendEnum for an
example.

Change-Id: Id29be92c343c10fd604683a80c5d5bd2bd070cb0
Bug: skia:11097
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/345419
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
10 files changed