I realized that bug 730209 doesn't support BCP 47 language tags that make use of extensions or private use subtags. At present, if such a language tag is the name of a dictionary, it will (I believe) display the entire language tag raw. A better behavior, I think, would be to simply ignore the extension and privateuse subtags if they are unsupported (which they currently are). In addition, the tests included in that bug are not as exhaustive as they could be, so that should also be improved. (I have code for this already; patch will be attached shortly.)

Updates the regexp and adds a bunch of tests.

Comment on attachment 611861 [details] [diff] [review] Improve support for extension and privateuse subtags rs=me

Pushed to try: https://tbpl.mozilla.org/?tree=Try&rev=ba49a841ccef

Ugh, I forgot to mention explicitly that this code presupposes the code for bug 716321. Since that code is not yet in m-i/m-c, I think we'll wind up with a failing test. The test on line 106 of toolkit/content/tests/browser/browser_InlineSpellChecker.js ('es-419') should be marked as todo_is.

Changed the test to todo_is. https://hg.mozilla.org/integration/mozilla-inbound/rev/031f54b05818

Here's the patch with the change integrated into, in case it's needed.

and https://hg.mozilla.org/mozilla-central/rev/031f54b05818