Harden SerializedImageFilter fuzzer against filter creation failure

Change-Id: Ic9cc0e17af55300a0de4eab7a61d150f2c07314a
Reviewed-on: https://skia-review.googlesource.com/154626
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
1 file changed