Add a method to search for the command that shades a pixel.

Supports a streamlined breakpoint workflow in the new debugger.
not used in the current debugger.

Change-Id: I9f30c92357c24e145a19c794e935e2c05594d883
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/332256
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Nathaniel Nifong <nifong@google.com>
1 file changed