Fix guard for the DrawableSubRun case

Some old code remained that checked for the container instead
of looking at creationBehavior.

Change-Id: I258e038f194f23d991d6d393eff332bd0bb2198a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/567116
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Herb Derby <herb@google.com>
1 file changed