class="{{ foo }" and :class="foo" not treated the same way during transitions.

[crswll]

In this example we're using class="{{ foo }}" in the template but the elements aren't transitioning.

http://jsfiddle.net/crswll/t5jv7d98/1/

If we use :class="foo" they transition just fine.

http://jsfiddle.net/crswll/t5jv7d98/2/