[infra-tests] Merge testharness.js (#5536)

@jgraham I did this with two commits: one to remove the submodule, and one to re-introduce the code via `git subtree add`. [This seems to be the popular approach](https://stackoverflow.com/questions/28215244/convert-git-submodule-to-subtree), but it also produces an invalid state in the history where the `resources` directory is absent. I'm not sure if this is a problem; if so, let me know, and I'll try to find a more advanced solution.

View on GitHub: https://github.com/w3c/web-platform-tests/pull/5536

Received on Tuesday, 11 April 2017 22:38:44 UTC