Automated g4 rollback of changelist 270896856.
Automated g4 rollback of changelist 270896856.

*** Reason for rollback ***

This breaks some tests:
https://screenshot.googleplex.com/iCW2mi2L7mC

*** Original change description ***

Update //third_party/dart_lang/v2 and macos_sdk to dbefc6c16572c5fd60d834147e505721a843e067.

***

PiperOrigin-RevId: 270906360

angulardart/angular,angulardart/angular,angulardart/angular