[turbofan] First steps towards optimizing for-in loops.

[turbofan] First steps towards optimizing for-in loops.

This is basically a port of the majority of optimizations that are
applied to for-in in full codegen. But it is not done during graph
building, but instead during typed lowering, which way less adhoc than
what the other compilers do.

Committed: https://crrev.com/017faaf451a43b13b0e2938a027b68a23d5773e4
Cr-Commit-Position: refs/heads/master@{#28726}

[Benedikt Meurer, 2015-06-01 10:29:28]

bmeurer@chromium.org changed reviewers:
+ jarin@chromium.org

[Benedikt Meurer, 2015-06-01 10:29:28]

Hey Jaro,

This is the port of the for-in stuff to typed lowering. It's pretty much
straight forward for now.
Please take a look.

Thanks,
Benedikt

[Jarin, 2015-06-01 11:24:55]

lgtm

[Benedikt Meurer, 2015-06-01 11:37:42]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2015-06-01 11:37:57]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1155313008/1

[commit-bot: I haz the power, 2015-06-01 11:41:24]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-06-01 11:41:36]

Patchset 1 (id:??) landed as
https://crrev.com/017faaf451a43b13b0e2938a027b68a23d5773e4
Cr-Commit-Position: refs/heads/master@{#28726}