Import testharness.js framework

from https://github.com/w3c/testharness.js/
commit b8c9ce09cd031e8a732bbfc0a8c81f674ffa8a49
Merge: 2e9c0e9 15f071f
Author: jgraham <james@hoppipolla.co.uk>
Date:   Tue Jun 10 06:48:07 2014 -0700