Revert "In RegExp, lastIndex is read with ToLength, not ToInteger"

Revert "In RegExp, lastIndex is read with ToLength, not ToInteger"

$toLength is slow, causing a 3.8%-8% regression in the Octane RegExp
benchmark. Reverting this patch brings it back up. To make this change,
we'll need a faster implementation fo $toLength.

BUG=chromium:513160
LOG=Y
R=adamk

Committed: https://crrev.com/477d651c6a978bdf34954048a235895c62dab0ac
Cr-Commit-Position: refs/heads/master@{#29830}

[adamk, 2015-07-24 00:32:24]

lgtm

[Dan Ehrenberg, 2015-07-24 00:33:35]

The CQ bit was checked by littledan@chromium.org

[commit-bot: I haz the power, 2015-07-24 03:54:42]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1243053005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1243053005/1

[commit-bot: I haz the power, 2015-07-24 06:21:11]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-24 06:21:37]

Patchset 1 (id:??) landed as
https://crrev.com/477d651c6a978bdf34954048a235895c62dab0ac
Cr-Commit-Position: refs/heads/master@{#29830}

[Michael Achenbach, 2015-07-24 08:25:43]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1254723005/ by machenbach@chromium.org.

The reason for reverting is: [Sheriff] This causes a breakage with custom
snapshot (bisected locally):
http://build.chromium.org/p/client.v8/builders/V8%20Linux64%20GC%20Stress%20-....

[Yang, 2015-07-27 08:37:26]

The CQ bit was checked by yangguo@chromium.org

[commit-bot: I haz the power, 2015-07-27 08:37:28]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1243053005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1243053005/1

[commit-bot: I haz the power, 2015-07-27 08:38:10]

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

[commit-bot: I haz the power, 2015-07-27 08:38:10]

Try jobs failed on following builders:
  v8_linux_rel on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux_rel/builds/7995)
  v8_mac_rel on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_mac_rel/builds/8104)
  v8_win_nosnap_shared_compile_rel on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_win_nosnap_shared_compil...)

[Yang, 2015-07-27 14:08:21]

On 2015/07/27 08:38:10, commit-bot: I haz the power wrote:
> Try jobs failed on following builders:
>   v8_linux_rel on tryserver.v8 (JOB_FAILED,
> http://build.chromium.org/p/tryserver.v8/builders/v8_linux_rel/builds/7995)
>   v8_mac_rel on tryserver.v8 (JOB_FAILED,
> http://build.chromium.org/p/tryserver.v8/builders/v8_mac_rel/builds/8104)
>   v8_win_nosnap_shared_compile_rel on tryserver.v8 (JOB_FAILED,
>
http://build.chromium.org/p/tryserver.v8/builders/v8_win_nosnap_shared_compil...)

Replaced by https://codereview.chromium.org/1256193002/