parse more css attribute match operators

Right now the cajoler fails to parse stuff like
  p[x$=y] {}
and the parse failure causes it to throw out a lot more css than it should.

Fixing the error recovery is somewhat nontrivial. Adding the new operators
is trivial.

Note, this just allows the operators to parse, but rejects them as not
allowed, similar to the |= operator. So, the operators still don't work,
but we recover from that better.

[ihab.awad, 2013-06-12 19:10:10]

Changes so far LGTM, but should not submit without adding support for the same
thing in ES5.

[felix8a, 2013-06-12 19:13:32]

On 2013/06/12 19:10:10, ihab.awad wrote:
> Changes so far LGTM, but should not submit without adding support for the same
> thing in ES5.

es5 already supports it.

[felix8a, 2013-06-12 19:17:33]

@r5445