Make SkTArray not allocate unless reserve or initial count > 0

This also makes it so that it doesn't shrink back into preallocated storage and therefore doesn't need to store the reserve count.

Change-Id: Ia320fed04c329641a5494947db39cefd2fb6d80f
Reviewed-on: https://skia-review.googlesource.com/9531
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
2 files changed