Extending SkUnicode API to avoid code duplication

Change-Id: I665475f828556c25271dc1dcf3feae8e0f2e4a9e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/712438
Commit-Queue: Julia Lavrova <jlavrova@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
11 files changed