Twenty Fourteen: fix two usability issues with touch events on mobile devices with the Featured Content slider:

 * Try to avoid the slight delay when swiping from one slide to the next.
 * Fix bug where second to last slide was animating like it was the last.

Fixes #26191.

git-svn-id: https://develop.svn.wordpress.org/trunk@26665 602fd350-edb4-49c9-b593-d223f7449a82