Used when the objects being compared can pass safely across isolate boundaries. If the object being
compared cannot safely cross isolate boundaries, then use DiffDelegate instead.
A specialized DiffEquality implementation that checks whether either object is Diffable and uses the delegate
check. If neither instance is Diffable, a fallback Equality is used
Dart makes it difficult to pass function pointers across isolates. DiffEquality provides a concrete implementation
of equality comparators that can be used safely across isolate boundaries.
