Avoid malloc calls for these two temp arrays on the stack.

TODO: fRunsInVisualOrder is a long-lived array, but appears to..
- never resize after the constructor
- very often be size==1
Can we preallocate storage for it in the TextLine itself? (e.g. StSTArray or other trick)

Change-Id: I817b46a24e01ddf999bdd81a607aaf35b3c0674b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/291776
Reviewed-by: Ben Wagner <bungeman@google.com>
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Reed <reed@google.com>
2 files changed