Run constant propagation one more time after canonicalization so that following code can always ret…

Run constant propagation one more time after canonicalization so that following code can always return true:

foo() {
  var a = new List(0);
  return a.isEmpty();
}

Committed: https://code.google.com/p/dart/source/detail?r=21489

[srdjan, 2013-04-12 17:51:03]

The code for allocating growable array (var a = []) is now simpler.

[srdjan, 2013-04-12 18:45:54]

On 2013/04/12 17:51:03, srdjan wrote:
> The code for allocating growable array (var a = []) is now simpler.

Actually the code for allocation is the same....

[Vyacheslav Egorov (Google), 2013-04-15 11:27:32]

LGTM

I am starting to wonder if we just need to have an optimization fix point.
Repeating various phases manually becomes boring :-)

[srdjan, 2013-04-15 18:06:30]

Committed patchset #3 manually as r21489 (presubmit successful).