MDL-44719 libraries: Invalid call to ajaxenabled()

A bad conflict resolution in 7eaca5a
wiped this function from the deprecatedlib file. This patch
restores it.

But as we should not call any deprecated function in core we
also remove the its usage.

lib/deprecatedlib.php

@@ -4335,3 +4335,17 @@ function can_use_html_editor() {
     debugging('can_use_html_editor has been deprecated please update your code to assume it returns true.', DEBUG_DEVELOPER);
     return true;
 }
+
+/**
+ * Returns whether ajax is enabled/allowed or not.
+ * This function is deprecated and always returns true.
+ *
+ * @param array $unused - not used any more.
+ * @return bool
+ * @deprecated since 2.7 MDL-33099 - please do not use this function any more.
+ * @todo MDL-44088 This will be removed in Moodle 2.9.
+ */
+function ajaxenabled(array $browsers = null) {
+    debugging('ajaxenabled() is deprecated - please update your code to assume it returns true.', DEBUG_DEVELOPER);
+    return true;
+}

tag/edit.php

@@ -162,8 +162,7 @@
 
 $tagform->display();
 
-if (ajaxenabled()) {
-    $PAGE->requires->js('/tag/tag.js');
-    $PAGE->requires->js_function_call('init_tag_autocomplete', null, true);
-}
+$PAGE->requires->js('/tag/tag.js');
+$PAGE->requires->js_function_call('init_tag_autocomplete', null, true);
+
 echo $OUTPUT->footer();