prealloc space for a simple fRunsInVisualOrder

Change-Id: I38e5ffbecdf5ca6870ccaccf43be149675a1d638
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/291972
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Mike Reed <reed@google.com>
1 file changed