jquery.ui: Collapse border in ui-helper-clearfix

Backport of upstream change released in jQuery UI v1.10.1
* http://bugs.jqueryui.com/ticket/8442
* https://github.com/jquery/jquery-ui/commit/cb42ee7ccd

This fixes the currently broken display of the media player in the
Listen template on en.wikipedia.org.

Bug: 71601
Change-Id: Ib3e0fc577c3f617955d6d12335a333587c6ddaa8
Merge "jquery.ui: Collapse border in ui-helper-clearfix"