[intl] Check for duplicate BCP 47 tags in a case-insensitive way

[intl] Check for duplicate BCP 47 tags in a case-insensitive way

Intl constructors are specified to prohibit structurally invalid
subtags. BCP 47 defines itself to be case-insensitive. Firefox does
throw on case-insensitive duplicates, following the specifications.
This patch makes V8 do the same. There is some small compatibility
risk, but the case is fairly niche, so I hope it does not cause
much breakage.

BUG=v8:4215
Review-Url: https://codereview.chromium.org/2639333003
Cr-Commit-Position: refs/heads/master@{#42487}
Committed: https://chromium.googlesource.com/v8/v8/+/5e60bfb29d38d431a2bf6699f8ce040a396673c8

[Dan Ehrenberg, 2017-01-18 19:46:25]

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

[commit-bot: I haz the power, 2017-01-18 19:46:36]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[Dan Ehrenberg, 2017-01-18 19:48:04]

littledan@chromium.org changed reviewers:
+ jungshik@google.com

[commit-bot: I haz the power, 2017-01-18 20:13:01]

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

[commit-bot: I haz the power, 2017-01-18 20:13:04]

Dry run: This issue passed the CQ dry run.

[jungshik at Google, 2017-01-19 04:24:43]

On 2017/01/18 19:48:04, Dan Ehrenberg wrote:

Lgtm

[jungshik at Google, 2017-01-19 04:24:59]

The CQ bit was checked by jshin@chromium.org

[commit-bot: I haz the power, 2017-01-19 04:25:07]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-01-19 04:27:05]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1484799899298000, "parent_rev":
"037200e6250d5ea6fbd4f5071615c8c850e5a661", "commit_rev":
"5e60bfb29d38d431a2bf6699f8ce040a396673c8"}

[commit-bot: I haz the power, 2017-01-19 04:27:11]

Description was changed from

==========
[intl] Check for duplicate BCP 47 tags in a case-insensitive way

Intl constructors are specified to prohibit structurally invalid
subtags. BCP 47 defines itself to be case-insensitive. Firefox does
throw on case-insensitive duplicates, following the specifications.
This patch makes V8 do the same. There is some small compatibility
risk, but the case is fairly niche, so I hope it does not cause
much breakage.

BUG=v8:4215
==========

to

==========
[intl] Check for duplicate BCP 47 tags in a case-insensitive way

Intl constructors are specified to prohibit structurally invalid
subtags. BCP 47 defines itself to be case-insensitive. Firefox does
throw on case-insensitive duplicates, following the specifications.
This patch makes V8 do the same. There is some small compatibility
risk, but the case is fairly niche, so I hope it does not cause
much breakage.

BUG=v8:4215

Review-Url: https://codereview.chromium.org/2639333003
Cr-Commit-Position: refs/heads/master@{#42487}
Committed:
https://chromium.googlesource.com/v8/v8/+/5e60bfb29d38d431a2bf6699f8ce040a396...
==========

[commit-bot: I haz the power, 2017-01-19 04:27:12]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/v8/v8/+/5e60bfb29d38d431a2bf6699f8ce040a396...