Use STArray for SkMesh child array.

This will improve efficiency for the relatively common case of a
single child.

Change-Id: I116e1f84b3b41efd9495c698704404c863ef53f3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/775837
Commit-Queue: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
2 files changed