Get rid of BidiUtils as a class holding only static methods. I was reminded by

Get rid of BidiUtils as a class holding only static methods. I was reminded by
this dart style quiz (third slide:
http://data-prez.appspot.com/deck/id=agtzfmRhdGEtcHJlenIRCxIJU2xpZGVEZWNrGKm6BAw&slide=2?locale=en).
Committed: https://code.google.com/p/dart/source/detail?r=9222

[Emily Fortuna, 2012-06-28 17:54:03]

I was taking that dart style quiz, and was reminded that I shouldn't have a
class that's just a bunch of static methods (it was written this way because I
ported it from Closure and wasn't thinking about changing the design too much).
Anyway, these just makes the BidiUtils class functions "top level functions" in
this library.

[Bob Nystrom, 2012-06-28 18:09:19]

I'm assuming this is just hoisting stuff to the top level, so I didn't read the
code in detail. Given that, LGTM!

[Alan Knight, 2012-06-28 18:29:21]

Apparently these sorts of changes are deeply confusing for the differencing
algorithm. LGTM.