Remove some unnecessary #includes of SkImageFilter.h

R=robertphillips@google.com
TBR=reed@google.com
BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1907283002

Review URL: https://codereview.chromium.org/1907283002
3 files changed