Fix the merge of locals handler logic.

Fix the merge of locals handler logic.

This currently works because there is no inferrer that make use of the creation of phis. I'm working on an experimental one that found these problems.

R=kasperl@google.com

Committed: https://code.google.com/p/dart/source/detail?r=27104

[ngeoffray, 2013-08-29 10:54:59]

https://codereview.chromium.org/23656005/diff/3001/sdk/lib/_internal/compiler...
File sdk/lib/_internal/compiler/implementation/types/simple_types_inferrer.dart
(left):

https://codereview.chromium.org/23656005/diff/3001/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/types/simple_types_inferrer.dart:2299:
// iterable.
This was actually too defensive. currentType will not be used at runtime if
there is no element in the iterable.

[ngeoffray, 2013-09-04 07:43:34]

Kasper, Peter and Karl being away, could you please take a look?

[kasperl, 2013-09-04 08:04:43]

LGTM!

[ngeoffray, 2013-09-04 09:25:39]

Committed patchset #2 manually as r27104 (presubmit successful).

[ahe, 2013-09-04 12:03:29]

Sorry for not replying sooner. I think I mostly understand what you're doing, so
LGTM!