Thread up two new V8 UseCounters for ES2015 RegExp compat

Thread up two new V8 UseCounters for ES2015 RegExp compat

These UseCounters were added in the V8 patch at
https://codereview.chromium.org/1545633002
They track how often web compatibility-driven workarounds to the
ES2015 spec are triggered. If the frequency goes down over time,
then we can remove one or both of them.

R=japhet@chromium.org
CC=yangguo
BUG=v8:4637, v8:4617
Committed: https://crrev.com/3cdcef55d54c954da0eb448301ba53ee23ea37f4
Cr-Commit-Position: refs/heads/master@{#366891}

[haraken, 2015-12-26 01:36:52]

LGTM

[Dan Ehrenberg, 2015-12-26 02:58:58]

The CQ bit was checked by littledan@chromium.org

[commit-bot: I haz the power, 2015-12-26 02:59:06]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1547143002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1547143002/1

[commit-bot: I haz the power, 2015-12-26 04:19:31]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-12-26 04:20:58]

Description was changed from

==========
Thread up two new V8 UseCounters for ES2015 RegExp compat

These UseCounters were added in the V8 patch at
https://codereview.chromium.org/1545633002
They track how often web compatibility-driven workarounds to the
ES2015 spec are triggered. If the frequency goes down over time,
then we can remove one or both of them.

R=japhet@chromium.org
CC=yangguo
BUG=v8:4637,v8:4617
==========

to

==========
Thread up two new V8 UseCounters for ES2015 RegExp compat

These UseCounters were added in the V8 patch at
https://codereview.chromium.org/1545633002
They track how often web compatibility-driven workarounds to the
ES2015 spec are triggered. If the frequency goes down over time,
then we can remove one or both of them.

R=japhet@chromium.org
CC=yangguo
BUG=v8:4637,v8:4617

Committed: https://crrev.com/3cdcef55d54c954da0eb448301ba53ee23ea37f4
Cr-Commit-Position: refs/heads/master@{#366891}
==========

[commit-bot: I haz the power, 2015-12-26 04:20:59]

Patchset 1 (id:??) landed as
https://crrev.com/3cdcef55d54c954da0eb448301ba53ee23ea37f4
Cr-Commit-Position: refs/heads/master@{#366891}

[Rick Byers, 2016-01-04 18:52:32]

On 2015/12/26 04:20:59, commit-bot: I haz the power wrote:
> Patchset 1 (id:??) landed as
> https://crrev.com/3cdcef55d54c954da0eb448301ba53ee23ea37f4
> Cr-Commit-Position: refs/heads/master@{#366891}

Note that this CL failed to follow the instructions in UseCounter.h for updating
histograms.xml.  The histograms.xml updates for this change are currently lumped
into my CL here: https://codereview.chromium.org/1554963003/