That we need to use the title element in the head section is not only
BEST PRACTICE, which I have learned is out of scope in this context,
but the spec actually says:
6.1 Required Elements
"Every polyglot markup document contains an html, head, title, and
body element."
We _need_ an assertion for DOCTYPE. You forgot that we can have a
DOCTYPE looking like the following:
<!DOCTYPE HTML>
The above is valid HTML5, it is well-formed even if the top-element is
lower-case, but the Polyglot Spec explicitly says:
4. DOCTYPE
"The string html is in lowercase letters."
Cheers
Jesper Tverskov
http://www.xmlplease.com
