Polymer/mdv — pull request #129 by jmesserly (2013-07-25 18:33:29+00:00)
Title: Add support for empty if, similar to bind and repeat.

Now that `if` implies `bind`, it seems natural if they have the same behavior when the attribute is empty. This gives an easy answer to cases like the one in https://github.com/Polymer/mdv/issues/128.