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.
Built from https://develop.svn.wordpress.org/trunk@26665


git-svn-id: http://core.svn.wordpress.org/trunk@26555 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Fourteen: remove unused variable in slider.js, see #26191.
Built from https://develop.svn.wordpress.org/trunk@26666


git-svn-id: http://core.svn.wordpress.org/trunk@26556 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Merge remote-tracking branch 'upstream/master'