SkMergeImageFilter: fModes might be nullptr

Bug:714994

Change-Id: Ib8349e8fc0aba455472035c9a4e873a1720b73e0
Reviewed-on: https://skia-review.googlesource.com/14267
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Matt Sarett <msarett@google.com>
1 file changed