CupertinoTabBar requires Localizations parent

Summary

Context

Migration guide

Timeline

References

Summary

Instances of CupertinoTabBar must have a
Localizationsparent in order to provide a localized
Semantics hint. Trying to instantiate  a
CupertinoTabBar without localizations 
results in an assertion such as the following:

Context

To support localized semantics information,
the CupertinoTabBar requires localizations.

Before this change, the Semantics hint provided
to the CupertinoTabBar was a hard-coded String,
‘tab, $index of $total’. The content of the semantics
hint was also updated from this original
String to ‘Tab $index of $total’ in English.