Migrate EliminateDeadLocalVariables into Transform.

Change-Id: Idc0c51c0d293121fd306e7153b2e47f7e7dec222
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/456646
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
5 files changed