Create RAII mechanism for continue-mask management.

This lets us share continue-mask logic across the for-loop and
do-loop implementations.

Change-Id: I2206bd370e9c2d0ee29f55073598ad0bcc705d5b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/635496
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
1 file changed