
          container.classList.add('horizontal');
          container.classList.add('wrap');
          container.classList.add('small');
          assert.isTrue(positionEquals(container, 0, 100, 0, 120), "container position ok");
          // |c1| |c2|
          // |c3|
          assert.isTrue(positionEquals(c1, 0, 50, 0, 50), "child 1 position ok");
          assert.isTrue(positionEquals(c2, 0, 50, 50, 100), "child 2 position ok");
          assert.isTrue(positionEquals(c3, 50, 100, 0, 50), "child 3 positi