Decided to merge the arrow tests back into one

I've changed my mind about having two tests for arrows and lexical this.
Now they're back in the same test, as per the former arrow test pullreq.
(In this case, Chrome 37+ is now failing the test, but the V8 team
[openly admits](http://code.google.com/p/v8/issues/detail?id=2700) that
their arrows aren't production-ready yet.)

Firefox's non-conformance regarding pedantic implementation details is
now noted in footnotes.

I've also converted the test code to a comment string, as per the
others.