1490a90bc1 Track guards using NullabilityNode rather than ConstraintVariable.
7f224d9fbe Track parameters that might need to be made optional/required using NullabilityNode.
6c063512ae Validate that nullability is propagated from optional/required named parameters.
ed7f524afb Refactor more of the migration tool to use NullabilityNode rather than ConstraintVariable.
78c55022b1 [VM] - Fix for issue 36484 exposed when ExperimentalFlag.constantUpdate2018 is turned on in CFE
a7175938c3 Remove use of package_root in analyzer/test/error_test
45a5349175 Track constant field initializers for field analysis.
91c042c066 Implement isCovariant for fields.