[tokenizer] handle `<<` correctly
[tokenizer] handle `<<` correctly

fixes MatthewMueller/cheerio#247
kirbysayshi/node-htmlparser,frontapp/htmlparser2,broadly/htmlparser2,frontapp/htmlparser2,mail-apps/htmlparser2,fasterize/node-htmlparser,magicode/htmlparser2,jasonsanjose/htmlparser2,mail-apps/htmlparser2,jasonsanjose/htmlparser2,broadly/htmlparser2,magicode/htmlparser2