Add in tabIndex to ensure that the tabbing works properly for link.

LMS-1311

common/static/js/src/accessibility_tools.js

@@ -110,11 +110,14 @@ var accessible_modal = function(trigger, closeButtonId, modalId, mainPageId) {
   });
 };
 
+// NOTE: This is a gross hack to make the skip links work for Webkit browsers
+// see http://stackoverflow.com/questions/6280399/skip-links-not-working-in-chrome/12720183#12720183
+
 // handle things properly for clicks
 jQuery('#skip-link a').click(function() {
     var href = jQuery(this).attr('href');
     if(href) {
-        jQuery(href).focus();
+        jQuery(href).attr('tabIndex', -1).focus();
     }
 });
 // and for the enter key
@@ -122,7 +125,7 @@ jQuery('#skip-link a').keypress(function(e) {
     if(e.which == 13) {
         var href = jQuery(this).attr('href');
         if(href) {
-            jQuery(href).focus();
+            jQuery(href).attr('tabIndex', -1).focus();
         }
     }
 });