Hack up SkShaper to pass additional callback info

- rename LineHandler -> RunHandler (since it gets called per run)
- pass additionl run info:

  * line index
  * cumulative advance
  * ascent/descent/leading

Bug: skia:
Change-Id: Ie848e5a35243088b99989c73fdec44c6a1bdd051
Reviewed-on: https://skia-review.googlesource.com/c/183300
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Florin Malita <fmalita@chromium.org>
7 files changed