tests[''] = function()

in src/main/lib/modernizr/modernizr.custom.js [210:221]


    tests['csstransforms3d'] = function() {

        var ret = !!testPropsAll('perspective');

                        if ( ret && 'webkitPerspective' in docElement.style ) {

                      injectElementWithStyles('@media (transform-3d),(-webkit-transform-3d){#modernizr{left:9px;position:absolute;height:3px;}}', function( node, rule ) {
            ret = node.offsetLeft === 9 && node.offsetHeight === 3;
          });
        }
        return ret;
    };