Document fuzzing setups

[jdm]

Known working:

• https://github.com/m0rt1c/servo-js-fuzz/
• https://github.com/fred-wang/servo-fuzzing
• https://github.com/googleprojectzero/domato (Random web content generator servo#20052 (comment))

[jdm]

A harness I'm using to run unmodified domato locally:

rm /tmp/fuzzing/*
python3 $1/generator.py --output_dir /tmp/fuzzing -n $3 >/dev/null
cd $2
for x in /tmp/fuzzing/*; do
  command="./mach run -r --headless -x -f --enable-experimental-web-platform-features --pref dom_servo_helpers_enabled /tmp/fuzzing/$x"
  eval $command >/tmp/fuzzout 2>&1 || (echo "$command"; cat /tmp/fuzzout)
done

[jdm]

Also worth looking into further:

• https://github.com/mateon1/reduce-binsrch
• https://github.com/mateon1/reduce-runner