Rewrite CheckModifiers to reduce code bloat

On my Linux-Release build, this cuts out 13K of code.

Change-Id: I4f470b148816441850400cafacd9fdf6c845ac0d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/438221
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
1 file changed