Within Google, closure compiler is used for dealing with translations.
We generate a closure-compatible locale file that allows for
registration within Angular, so that Closure i18n works well together
with Angular applications. Closure compiler does not limit its
locales to BCP47-canonical locale identifiers. This commit updates
the generation logic so that we also support deprecated (but aliased)
locale identifiers, or other aliases which are likely used within
Closure. We use CLDR's alias supplemental data for this. It instructs
us to alias `iw` to `he` for example. `iw` is still supported in Closure.
Note that we do not manually extract all locales supported in Closure;
instead we only support the CLDR canonical locales (as done before) +
common aliases that CLDR provides data for. We are not aware of other
locale aliases within Closure that wouldn't be part of the CLDR aliases.
If there would be, then Angular/Closure would fail accordingly.
PR Close#42230
9d1deb16fa