fix(a): workaround IE bug affecting mailto urls

Apparently there is a really weird bug in IE6-8 that causes anchor textContent
to be reset with href content when both contain @ symbol.

Inserting a bogus comment node into all anchor elements in IE works around this
browser bug.

I'm fixing the issue via directive because that way we'll fix it for jQuery as
well.

I fixed an e2e test too because it was incorrect.

Closes #1949