Removed unused/nonexistent methods from IRGenerator

Change-Id: Idedc91b5b21a0cba162c14f0a37b72650aa91c81
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/455256
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
2 files changed