sk_app, editor: cursor blink

Change-Id: I43044727298265ddb711456346c2b544ca8d509d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/231477
Commit-Queue: Hal Canary <halcanary@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Auto-Submit: Hal Canary <halcanary@google.com>
2 files changed