Fixed skslc assertion failure discovered by fuzzer

This particular issue probably wouldn't ever occur in hand-written code, but
such is fuzzing...

Bug: oss-fuzz:17061
Change-Id: Ia5da7b75afef8b49bb19ddb7f1ea8696053c2e54
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/240197
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
1 file changed