remove doc reference to (now deleted) class

Bug: skia:
Change-Id: I4e75ff69d425442eb036462d9bab3c367d4bfa22
Reviewed-on: https://skia-review.googlesource.com/97664
Commit-Queue: Cary Clark <caryclark@google.com>
Reviewed-by: Cary Clark <caryclark@google.com>
1 file changed