Fix env test to check for proper exception

The test didn't check for what it actually wanted to test. The contained
code did actually throw, however that was only the case, because jsdom
was undefined, instead of a thrown error by jsdom.env.
Add more clearity to tests run by the w3c suite

Pages where script errors occur will now result in a failed test and
successful assertions will also be counted.
localName should not be null for ELEMENT_NODE
Add document.implementation.createHTMLDocument()
Add a note about how to update the web-platform-tests submodules
Version 1.1.0