c80b91dcdeb841e36e13119358a967376cb054c7
Adds `Locale.toLanguageTag()`, which returns a valid Unicode Locale Identifier using underscores as separator that can be reliably parsed.
Description
Languages
Dart
75.4%
C++
16.4%
Objective-C++
2.7%
Java
2.7%
Objective-C
0.6%
Other
1.8%