Format of candidate-attribute string

According to the latest editor's draft, section 4.8.1.1, the candidate
field is defined as follows:

   candidate of type DOMString, nullable
   This carries the candidate-attribute as defined in section 15.1 of [ICE].

In other words, candidate-attribute is just "candidate:<blah>", not
"a=candidate:<blah>CRLF".

However, Chrome currently emits and expects to receive candidates of
type "a=candidate:<blah>CRLF". Naturally, this is not trivially
changeable, although we could transition this over a series of Chrome
releases.

So the question becomes: is this (i.e., no a=) what was originally
intended? If so, is this something we want to change?

Firefox doesn't currently emit trickle candidates, and it could be
made to handle either incoming format, so regardless of whether we
choose to use a= or not, we have an opportunity to resolve this issue
without breaking the world.