Escape HTML when rendering AJAX error

Signed-off-by: Michal Čihař <michal@cihar.com>

js/ajax.js

@@ -808,8 +808,8 @@ $(document).ajaxError(function(event, request, settings){
         PMA_ajaxShowMessage(
             '<div class="error">'
             + PMA_messages['strErrorProcessingRequest']
-            + '<div>' + errorCode + '</div>'
-            + '<div>' + errorText + '</div>'
+            + '<div>' + escapeHtml(errorCode) + '</div>'
+            + '<div>' + escapeHtml(errorText) + '</div>'
             + '</div>',
             false
         );