[es6] Implement Reflect.enumerate.

[es6] Implement Reflect.enumerate.

R=rossberg
BUG=v8:3931
LOG=n

Committed: https://crrev.com/2ed1eebe9ff1804afcfb563bd51ef44e76629755
Cr-Commit-Position: refs/heads/master@{#31299}

[neis, 2015-10-15 08:40:49]

PTAL.

A comment on tests:

test262 has a bunch of tests for Reflect, including Reflect.enumerate.  I'm not
sure if we can enable them because they would require the --harmony-reflect
flag.

I have manually run these tests (for Reflect.enumerate) on this CL and they all
pass except for one that needs proxies.

[rossberg, 2015-10-15 12:05:45]

lgtm

[neis, 2015-10-15 12:09:26]

The CQ bit was checked by neis@chromium.org

[commit-bot: I haz the power, 2015-10-15 12:09:36]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1397443013/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1397443013/1

[commit-bot: I haz the power, 2015-10-15 12:59:32]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-15 12:59:50]

Patchset 1 (id:??) landed as
https://crrev.com/2ed1eebe9ff1804afcfb563bd51ef44e76629755
Cr-Commit-Position: refs/heads/master@{#31299}