c62534fc03
This removes the "unset" values and uses nullable types instead. The names and uses of the pattern fields are normalized, using `matchedValueType`, `requiredType` and `lookupType` consistently between [Pattern] subclasses. TEST=existing Change-Id: Ic79ce17075aa8ce252e1c223b59bef660f32bb7c Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/288704 Commit-Queue: Johnni Winther <johnniwinther@google.com> Reviewed-by: Chloe Stefantsova <cstefantsova@google.com> Reviewed-by: Alexander Markov <alexmarkov@google.com>