[turbofan] Unstable prototype maps are not supported currently.

[turbofan] Unstable prototype maps are not supported currently.

We currently assume that all prototype maps are stable, which is
not guaranteed for certain keyed access patterns. So we explicitly
disallow optimizing the element access there for now.

BUG=chromium:557807, v8:4470
R=jarin@chromium.org
LOG=n

Committed: https://crrev.com/3c9ac974f23cd1fd92f4bc46a2b2bef2c988cf2f
Cr-Commit-Position: refs/heads/master@{#32101}

[Jarin, 2015-11-19 05:26:31]

lgtm

[Benedikt Meurer, 2015-11-19 05:34:47]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2015-11-19 05:34:54]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1456973004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1456973004/1

[commit-bot: I haz the power, 2015-11-19 06:20:41]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-19 06:21:13]

Patchset 1 (id:??) landed as
https://crrev.com/3c9ac974f23cd1fd92f4bc46a2b2bef2c988cf2f
Cr-Commit-Position: refs/heads/master@{#32101}