This allows the parser to parse constant patterns at lower precedence
level in order to recognize more expressions in this context. To
support this, _parsePrecedenceExpressionLoop special cases a few cases
that should _not_ be parsed as expression in a constant pattern context.
Closes#50996
Change-Id: I43bb0ce52d366bd2dfcf47e12eec5883402f668a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/282100
Commit-Queue: Johnni Winther <johnniwinther@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Jens Johansen <jensj@google.com>