We already assert that setCount()'s argument is non-negative.
This does the same for setReserve().
There was one call site I could find that was actually sometimes
passing negative values to setReserve(), guarded here.
Already reviewed: https://skia-review.googlesource.com/c/skia/+/115982
Change-Id: Ia52a286732bf4056e9baf09555d27bab9abf2554
Reviewed-on: https://skia-review.googlesource.com/122305
Reviewed-by: Mike Klein <mtklein@chromium.org>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
23e4544e94