adding elasticY for a test

as part of fix for dc-js#1056

Author: gazal-k

spec/composite-chart-spec.js

@@ -644,6 +644,7 @@ describe('dc.compositeChart', function () {
           describe('with alignYAxes', function () {
               beforeEach(function () {
                   chart.alignYAxes(true)
+                      .elasticY(true)
                       .render();
               });
               it('the axis baselines should match', function () {