Function scroll

test/jasmine/tests/gl2d_plot_interact_test.js:681–686

(target, amt)

        var relayoutCallback = jasmine.createSpy('relayoutCallback');

        function scroll(target, amt) {
            return new Promise(function(resolve) {
                target.dispatchEvent(new WheelEvent('wheel', {deltaY: amt || 1, cancelable: true}));
                setTimeout(resolve, 0);
            });
        }

        function touchDrag(target, start, end) {
            return new Promise(function(resolve) {