This method is called every time we paint a styled text range to find its cluster range.
Instead of scanning all the clusters in the run we can use
a helper table that for every UTF8 byte keeps its cluster.
(So the most important part of the change is this table in Paragraph)
Should have done it long time ago but fixing bugs seemed to be more
important than performance.
Change-Id: I309f18ace4654b140a8532fef415c0280ea09d08
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/295005
Commit-Queue: Julia Lavrova <jlavrova@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
Reviewed-by: Mike Reed <reed@google.com>
e2c83a323a