fix more fuzz, carsvg

Fix a few kevin-generated fuzzers.

Remove an assert triggered by
carsvg when thrown through the
distance field stuff.

TBR=reed@google.com
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2427253005

Review-Url: https://chromiumcodereview.appspot.com/2427253005
5 files changed