Introduce a Skottie JSON extension for controlling vertical text
alignment ("sk_vj"), with a single public value for now: 1 (centered).
Refactor SkottieShaper to handle vertical adjustments based on a VAlign
enum:
kTop - the topmost line is ascent-aligned with the box top
(AE text-box behavior)
kTopBaseline - the topmost line is baseline-aligned with the top box
(AE text-point behavior)
kCenter - the text center is aligned with the box center
("sk_vj": 1, Skottie extension)
Also externalize the vertical adjustment as a text blob offset (instead
of baking into blob glyph offsets).
Change-Id: I29a414d4c6ccfafc534ca7b61f48ef96d8cff86e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/205590
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Florin Malita <fmalita@chromium.org>
