Migrate Buffer peek*array methods to art.

This is the first half of part 2 from
https://b.corp.google.com/issues/176942060#comment4.
We will later use art internals to improve performance.

Test: m
Test: old (https://paste.googleplex.com/5268030335483904) vs new (https://paste.googleplex.com/6393930242326528) benchmark results
Bug: 176942060

Change-Id: I257ad28a5ef2c0f222ce65a30c8cf72e360d5e22
1 file changed