code: function atfontface() {
      var pos = position();
      var m = match(/^@font-face */);
      if (!m) return;
  
      if (!open()) return error("@font-face missing '{'");
      var decls = comments();
  
      // declarations
      var decl;
      while (decl = declaration()) {
        decls.push(decl);
        decls = decls.concat(comments());
      }
  
      if (!close()) return error("@font-face missing '}'");
  
      return pos({
        type: 'font-face',
        declarations: decls
      });
    }
docs: Parse font-face.