Re: Shadow DOM: Hat and Cat -- if that's your real name.

+1 to ::shadow and ::shadow-all

The Polymer team (polymer-project.org) just discussed this and we agree
that ::shadow and ::shadow-all is a reasonable compromise. That said, there
we prefer ^ and ^^ and noted a few drawbacks to changing to use these
pseudo-elements.

1. ::shadow and ::shadow-all are significantly more verbose (x-foo ^ .bar
v. x-foo::shadow .bar).
2. There's a semantic difference between the combinator and a
pseudo-element. 'x-foo ^' is clearly an error, 'x-foo::shadow' is not but
it styles nothing. If you mistakenly write 'x-foo ::shadow .bar' you'll
style something completely different than 'x-foo::shadow .bar'.
3. Related to the previous point, combinators fits more with what we're
conceptually doing. If I want to style .bar inside x-foo's shadowRoot,
there's a known relationship between .bar and x-foo.