Prevents introduction of a bug when modifying a type that is used
with one of these containers in such way that makes the use
unsafe.
Change-Id: I959e6f3bfbc9664a6b0ced636f5ae6cbe72eee1a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/390676
Reviewed-by: Herb Derby <herb@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
a6ca0b1354