Remove TArray::reserve_back.

We now have `TArray::reserve`, which matches the behavior of
`vector::reserve`, and `TArray::reserve_exact`, which reserves
the exact number of elements that the user asks for.

Bug: skia:14316
Change-Id: I284e7cbe99e52d2c2fafd42204df7a7ab0aa994b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/709203
Auto-Submit: John Stiles <johnstiles@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
Reviewed-by: Herb Derby <herb@google.com>
2 files changed