fix(jqLite): ignore class methods on comment elements

Since c785267e jqLite uses setAttribute (rather than className property) in order to change classes. Some elements (eg. Comment) do not have this method which blows up.

jQuery silently ignores these method calls (because it uses className), so to get the same behavior as jQuery, we check for setAttribute method first.
feat(ngRepeat): use block separator comments

Issue: multi-elements ng-repeat (ng-repeat-start, ng-repeat-end) can contain elements with a trancluding directive. This directive changes content of the row (template) and ng-repeat does not work correctly (when removing/moving rows), because ng-repeat works with the original template (elements).

This changes ng-repeat behavior to traverse the DOM to find current elements everytime we are moving/removing rows (if the template has multiple elements).

Closes #3104