Import latest from html5lib-tests. Replaces #1195

This doesn't yet filter out the #script-off tests. See #1203.
Drop extraneous LF from expected test result.
Merge pull request #1204 from w3c/submission/sideshowbarker/html5lib-test-update

Import latest from html5lib-tests. Replaces #1195
Skip html5lib script-off tests. Closes #1203.
Merge pull request #1206 from w3c/submission/sideshowbarker/script-off

Skip html5lib script-off tests. Closes #1203.
Add tests for null/undefined/empty string namespace arguments to Document.createElementNS.
Use correct English in Document-createElementNS.html.
Merge pull request #1207 from Ms2ger/createElementNS-null-ns

Add tests for null/undefined/empty string namespace arguments to Document.createElementNS; r=zcorpan