initialize to avoid Valgrind false positive

I don't think it makes things any slower, less clear, or less safe to
initialize this `isClosed` variable.  I'd be inclined to leave it this
way even if hypothetically we roll to a newer Valgrind that can analyze
this correctly.

For background see
https://internals.rust-lang.org/t/valgrind-memcheck-false-positive-fixes-for-rust/11166

Change-Id: Ifef9417733824b857d4407c45c92c017d189a8fa
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/255354
Commit-Queue: Mike Klein <mtklein@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
Auto-Submit: Mike Klein <mtklein@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
1 file changed