Make sure all loop-phis are declared.

Make sure all loop-phis are declared.

Committed: https://code.google.com/p/dart/source/detail?r=7484

[floitsch, 2012-05-09 16:28:05]

This fixes self-hosted dart2js.
The problem was that some loop-phis weren't declared and thus using the
implicitly defined global variables:

$.foo = function() {
  for (var x = true, i = 0; i < 3; x = x0, i = i0) {
    x0 = x;  // <========= no "var" for x0.
...

[Lasse Reichstein Nielsen, 2012-05-10 11:02:04]

lgtm