Use SkTHashMap to implement DefinitionMap.

The benchmarks show a negligible performance decrease over the bespoke
TinyUnorderedMap class, but it's well within the margin of error, and
a real hash map will scale better in pathological cases.

Nanobench: http://screen/537ETJivpGdVJpk

Change-Id: I21279c47742a5dac81d57c7e9f7da4bfc595fdc9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/323114
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
6 files changed