Retrying r10475 (now with null check):

Retrying r10475 (now with null check):
Continue work on type propagation in optimizing compiler (still WIP).
Propagated types are cached in ssa definition nodes.
Type propagation iterates until fix point is reached.
Type checks are marked as eliminated when possible.
Committed: https://code.google.com/p/dart/source/detail?r=10478

[regis, 2012-08-10 01:25:28]

TBR

[srdjan, 2012-08-10 17:10:42]

lgtm