Guidelines

Setting up

Run git submodule foreach git pull origin master to fetch whatwg submodule.
- then run git submodule foreach git submodule update --recursive to update submodules in the submodle.
npm run build builds the dist files.
Dist files are stored in dist folder and checked into git so they are downloadable from the repository page.
npm test runs reference implementation tests.

No changes are to be made to the submodule files directly.
The polyfill API interface must remian backward compatible.
If submodule upstream changes, update the submodule, commit the ref and rebuild dist files.