[turbofan] Fix overly aggressive keyed access lowering.

[turbofan] Fix overly aggressive keyed access lowering.

The keyed load/store lowering is too aggressive when it comes to element
vs. property access. If we cannot find a cached name on the IC we
automatically assume that it's an element access, i.e. we assume that
the key that is passed to the keyed access must be a valid array index
then. But this is not true for megamorphic keyed load/store ICs, which
do not have a cached name (because the IC saw different names), and thus
use a different mechanism to indicate that it's a non-element access.

Committed: https://crrev.com/c987284af0c57fcb42771d2a8119ad36b8feca2d
Cr-Commit-Position: refs/heads/master@{#38155}

[Benedikt Meurer, 2016-07-29 04:35:45]

The CQ bit was checked by bmeurer@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-07-29 04:35:48]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-07-29 05:19:28]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-07-29 05:19:29]

Dry run: This issue passed the CQ dry run.

[Yang, 2016-07-29 06:01:42]

yangguo@chromium.org changed reviewers:
+ yangguo@chromium.org

[Yang, 2016-07-29 06:01:43]

lgtm

[Benedikt Meurer, 2016-07-29 06:30:35]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2016-07-29 06:30:39]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-07-29 06:32:07]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-07-29 06:34:48]

Description was changed from

==========
[turbofan] Fix overly aggressive keyed access lowering.

The keyed load/store lowering is too aggressive when it comes to element
vs. property access. If we cannot find a cached name on the IC we
automatically assume that it's an element access, i.e. we assume that
the key that is passed to the keyed access must be a valid array index
then. But this is not true for megamorphic keyed load/store ICs, which
do not have a cached name (because the IC saw different names), and thus
use a different mechanism to indicate that it's a non-element access.
==========

to

==========
[turbofan] Fix overly aggressive keyed access lowering.

The keyed load/store lowering is too aggressive when it comes to element
vs. property access. If we cannot find a cached name on the IC we
automatically assume that it's an element access, i.e. we assume that
the key that is passed to the keyed access must be a valid array index
then. But this is not true for megamorphic keyed load/store ICs, which
do not have a cached name (because the IC saw different names), and thus
use a different mechanism to indicate that it's a non-element access.

Committed: https://crrev.com/c987284af0c57fcb42771d2a8119ad36b8feca2d
Cr-Commit-Position: refs/heads/master@{#38155}
==========

[commit-bot: I haz the power, 2016-07-29 06:34:48]

Patchset 1 (id:??) landed as
https://crrev.com/c987284af0c57fcb42771d2a8119ad36b8feca2d
Cr-Commit-Position: refs/heads/master@{#38155}