Get the html source of messages from html_codesniffer

It is sometimes helpful to see the html source of a message returned by html_codensiffer.

I made these changes while trying to locate the source of a message in pa11y.  The message was present in pa11y, but wasn't being reported by html_codesniffer bookmarklet when I ran it in the browser, so I had no idea what the context of the error was.  (it turns out it was because phantomjs thinks it is a touch browser)