Remove obsolete comment about deepCopyTo

Bug: skia:
Change-Id: If5220248dbc505ff984d09833df7e18934d71438
Reviewed-on: https://skia-review.googlesource.com/20321
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
1 file changed