Convert statement arrays from std::vector to SkSTArray.

This will help us avoid allocations for arrays of statements.

Currently, this is a wash in Nanobench (~0% change). In the near
future, we expect to collapse the expression array and statement array
into a single hybrid array, and this helps bring us closer to that end
goal.

Change-Id: Id146907352799c41b568090ab65e454247b294c8
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/325625
Commit-Queue: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
11 files changed