Stage sloppy let

Stage sloppy let

Move the --harmony-sloppy-let flag to staging for further testing, and
update test262 for the new passing tests. Also increase the strictness
of the parser, even in sloppy mode, to disallow "new legacy compat" for

  for (let x = 5 in {}) {}

which is now a SyntaxError.

BUG=v8:3305
LOG=Y
R=adamk

Committed: https://crrev.com/a2841eb0dc1f9823faac46320ecae60aa5be0fe0
Cr-Commit-Position: refs/heads/master@{#30525}

[Dan Ehrenberg, 2015-09-01 19:05:54]

The CQ bit was checked by littledan@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-09-01 19:06:03]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1321013005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1321013005/1

[adamk, 2015-09-01 19:13:44]

lgtm

[commit-bot: I haz the power, 2015-09-01 19:31:33]

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

[commit-bot: I haz the power, 2015-09-01 19:31:34]

Dry run: This issue passed the CQ dry run.

[Dan Ehrenberg, 2015-09-01 20:01:20]

The CQ bit was checked by littledan@chromium.org

[commit-bot: I haz the power, 2015-09-01 20:01:37]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1321013005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1321013005/1

[commit-bot: I haz the power, 2015-09-01 20:03:20]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-01 20:03:37]

Patchset 1 (id:??) landed as
https://crrev.com/a2841eb0dc1f9823faac46320ecae60aa5be0fe0
Cr-Commit-Position: refs/heads/master@{#30525}