Theme base core: Updated clearfix to 'new micro clearfix hack' by Nic…

…olas Gallagher http://nicolasgallagher.com/micro-clearfix-hack/ . Fixed #7838 - Clearfix breaks after runs through YUI Compressor

(cherry picked from commit c21a5b4)

themes/base/jquery.ui.core.css

@@ -13,12 +13,9 @@
 .ui-helper-hidden { display: none; }
 .ui-helper-hidden-accessible { position: absolute !important; clip: rect(1px 1px 1px 1px); clip: rect(1px,1px,1px,1px); }
 .ui-helper-reset { margin: 0; padding: 0; border: 0; outline: 0; line-height: 1.3; text-decoration: none; font-size: 100%; list-style: none; }
-.ui-helper-clearfix:after { content: "."; display: block; height: 0; clear: both; visibility: hidden; }
-.ui-helper-clearfix { display: inline-block; }
-/* required comment for clearfix to work in Opera \*/
-* html .ui-helper-clearfix { height:1%; }
-.ui-helper-clearfix { display:block; }
-/* end clearfix */
+.ui-helper-clearfix:before, .ui-helper-clearfix:after { content: ""; display: table; }
+.ui-helper-clearfix:after { clear: both; }
+.ui-helper-clearfix { zoom: 1; }
 .ui-helper-zfix { width: 100%; height: 100%; top: 0; left: 0; position: absolute; opacity: 0; filter:Alpha(Opacity=0); }