mediawiki.html: Add broken tests for numbers and booleans

mediawiki.html: Add broken tests for numbers and booleans
* The following are broken right now:

mw.html.element( 'p', {}, 500 );
> Error: mw.html.element: Invalid type of contents
(custom error by mw.html.element)

mw.html.element( 'option', { selected: foo === bar }, 'label' );
> TypeError: Undefined method .replace

(bug 30774) - mediawiki.html: Add support for numbers and booleans