Verify user agents must allow external style sheets to be associated with the document using the LINK element.
The href attribute of the LINK element specifies the location of the style sheet file. The value of href is a URI.
The type attribute of the LINK element indicates the language of the linked resource, in this case a style sheet.
Test for assertion 14.3.2-1, 14.3.2-2, 14.3.2-3
This paragraph should be blue because blue.css is linked.