Issue #1687864 by sun, BarisW, mgifford, sebsebseb123: Bring theme_breadcrumb() up to WCAG 2.0 AA.

core/includes/theme.inc

@@ -1830,7 +1830,7 @@ function theme_breadcrumb($variables) {
     // Provide a navigational heading to give context for breadcrumb links to
     // screen-reader users. Make the heading invisible with .element-invisible.
     $output .= '<h2 class="element-invisible">' . t('You are here') . '</h2>';
-    $output .= '<ol><li>' . implode(' » </li><li>', $breadcrumb) . '</li></ol>';
+    $output .= '<ol><li>' . implode('</li><li>', $breadcrumb) . '</li></ol>';
     $output .= '</nav>';
   }
   return $output;

core/modules/system/system.theme.css

@@ -305,6 +305,13 @@ ul.inline li {
   margin: 0;
   padding: 0;
 }
+/* IE8 does not support :not() and :last-child. */
+.breadcrumb li:before {
+  content: ' » ';
+}
+.breadcrumb li:first-child:before {
+  content: none;
+}
 
 /**
  * Markup generated by theme_menu_local_tasks().