improved SkSL lexer performance

Bug: skia:
Change-Id: Ibbb427e511118a0a1819094a59c17cc0f966008c
Reviewed-on: https://skia-review.googlesource.com/145336
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
4 files changed