Alternative approach to using type feedback for Symbol-keyed properties

Alternative approach to using type feedback for Symbol-keyed properties

This patch only treats non-private symbols as valid feedback, thus
avoiding the need to switch to Oddballs for the feedback sentinels
and avoiding breaking the use of private own symbols.

Crankshaft will also optimize these symbol loads into a named load,
just as it does for string keyed loads with type feedback.

BUG=

Committed: https://crrev.com/e6626cfc671835f7786f3ab9f615b79b23331da6
Cr-Commit-Position: refs/heads/master@{#31496}

[mvstanton, 2015-10-23 07:49:12]

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

[mvstanton, 2015-10-23 07:49:12]

Hi Benedikt, here is the patch we discussed. Adam made the first rev, then I
added the crankshaft optimization support. I've decoupled this optimization from
bug 542504, which tracks the kraken regression we discussed.
--Michael

[Benedikt Meurer, 2015-10-23 07:51:25]

Nice. LGTM

[mvstanton, 2015-10-23 08:16:24]

The CQ bit was checked by mvstanton@chromium.org

[commit-bot: I haz the power, 2015-10-23 08:16:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1415333003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1415333003/1

[commit-bot: I haz the power, 2015-10-23 08:17:51]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-23 08:18:11]

Patchset 1 (id:??) landed as
https://crrev.com/e6626cfc671835f7786f3ab9f615b79b23331da6
Cr-Commit-Position: refs/heads/master@{#31496}