Some web-sys docs link to pages which don't exist - should point to the type instead

[martin-t]

Some properties and methods on MDN are only documented on the type's page and don't have a separate page. The generated docs, however, assume the pages exist.

Examples:
property: HtmlInputElement::height() should link to HTMLInputElement
inherited method: DomMatrix::rotate() should link to DOMMatrixReadOnly

[alexcrichton]

Currently the doc-link generation is pretty primitive, it just makes a blind guess about MDN and assume it's right. If others know how to improve the generated links that'd be good to update!