Vector-based KeyedLoadIC MISS logic needs improvement.

Vector-based KeyedLoadIC MISS logic needs improvement.

Two issues:
1) We would trace the MISS two times on vector-based KeyedLoadIC
   with a string key in MEGAMORPHIC state.
2) There was a confusing asymmetry in the handling of going
   GENERIC. This change makes it the same whether
   --vector-ics is on or not.

BUG=

Committed: https://crrev.com/b3b9d20ad76400f4c61748072ddda033655b4484
Cr-Commit-Position: refs/heads/master@{#26105}

[mvstanton, 2015-01-16 12:25:02]

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

[mvstanton, 2015-01-16 12:25:02]

Hi Yang, this CL cleans up some strange logic around changing to the GENERIC
state in the miss handler. Thanks for the look,
--Michael

[Yang, 2015-01-16 12:33:07]

lgtm.

[mvstanton, 2015-01-16 13:01:21]

The CQ bit was checked by mvstanton@chromium.org

[commit-bot: I haz the power, 2015-01-16 13:01:35]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/839893005/1

[commit-bot: I haz the power, 2015-01-16 13:28:27]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-16 13:28:37]

Patchset 1 (id:??) landed as
https://crrev.com/b3b9d20ad76400f4c61748072ddda033655b4484
Cr-Commit-Position: refs/heads/master@{#26105}