switched SkSL from std::map to std::unordered_map

This results in a significant performance win.

Bug: skia:
Change-Id: I52c92225fb3c1a06a649bd54f9578d305022d3a9
Reviewed-on: https://skia-review.googlesource.com/145155
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
5 files changed