Repeated elements do not work in AJAX forms

Find a form with repeated elements and make sure it works properly (for example, create a mod_choice activity)

To test repeated elements in the modal forms:

1. Pick commits from testing branch:

   git pull git://github.com/marinaglancy/moodle.git MDL-63685-master-testing

2. Open pages /tag/test1.php , /tag/test2.php , /tag/test3.php
3. Make sure the repeated elements work in all three forms:
   1. add data to them
   2. add more elements
   3. submit
   4. view the submission data