Something

Huh

css: function( url, exclude, callback, checkFn ){
        var scriptElement;
        checkFn = checkFn || function(){
          return !!scriptElement;
        };

        url = fixUrl( url );

        var interval;
        function f() {
          interval = setInterval(function(){
            if( checkFn() ){
              clearInterval( interval );
              if( callback ){
                callback();
              }
            }
          }, CSS_POLL_INTERVAL );
        }

        if( !checkFn() ){
          scriptElement = document.createElement( "link" );
          scriptElement.rel = "stylesheet";
          scriptElement.onload = f;
          scriptElement.href = url;
          document.head.appendChild( scriptElement );
        }
      }

Huh?

css: function( url, exclude, callback, checkFn ){
        var scriptElement;
        checkFn = checkFn || function(){
          return !!scriptElement;
        };

        url = fixUrl( url );

        if( !checkFn() ){
          scriptElement = document.createElement( "link" );
          scriptElement.rel = "stylesheet";
          scriptElement.href = url;
          //scriptElement.onload = callback;
          document.head.appendChild( scriptElement );
        }

        var interval = setInterval(function(){
          if( checkFn() ){
            clearInterval( interval );
            if( callback ){
              callback();
            }
          }
        }, CSS_POLL_INTERVAL );

      }