Internationalization API: LocaleList removal

[Norbert Lindenberg]

At the TC 39 meeting on May 21, we decided to remove LocaleList from the Internationalization API because its primary purpose is performance and we don't have evidence that there actually is a performance problem requiring this solution.

One side effect of removing LocaleList from the API is that the object returned from the supportedLocalesOf methods is now a simple Array, and therefore is modifiable. This probably prevents us from ever switching the return value of these methods back to a LocaleList, whose LocaleList properties (length and indexed elements 0..length-1) are immutable.

I don't think that's a big concern, but wanted to bring it to everybody's attention in case somebody does have concerns.

Norbert