There's no point in using an out-param (and shaving off a line or two from nsHTMLDocument::StartDocumentLoad is always nice). I'll fix if nobody beats me to it.
Note to self: mentioned on <https://developer.mozilla.org/en/Gecko/HTML_parser_threading>.
Created attachment 570632 [details] [diff] [review] Patch v1
Comment on attachment 570632 [details] [diff] [review] Patch v1 r=hsivonen if you revise the nsIParser interface ID.