tidy up SkRecord bounding code

  - remove unused fNumRecords field
  - remove unused getter methods
  - cleanUp() -> dtor

Change-Id: I1ade20e56cced40d511598a964ca362d7afc269c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/245600
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
1 file changed