Use clear instead of reset(0)

Change-Id: I63de93747c118b5c7fc3ebb8a84489a27088650e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/617640
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Herb Derby <herb@google.com>
1 file changed