Cleanup MatchState in pub.

sdk/lib/_internal/pub/test/version_test.dart

Index: sdk/lib/_internal/pub/test/version_test.dart
===================================================================
--- sdk/lib/_internal/pub/test/version_test.dart	(revision 24041)
+++ sdk/lib/_internal/pub/test/version_test.dart	(working copy)
@@ -430,14 +430,14 @@
 
   VersionConstraintMatcher(this._expected, this._allow);
 
-  bool matches(item, MatchState matchState) => (item is VersionConstraint) &&
+  bool matches(item, Map matchState) => (item is VersionConstraint) &&
       _expected.every((version) => item.allows(version) == _allow);
 
   Description describe(Description description) =>
       description.add(' ${_allow ? "allows" : "does not allow"} versions');
 
   Description describeMismatch(item, Description mismatchDescription,
-      MatchState matchState, bool verbose) {
+      Map matchState, bool verbose) {
     if (item is! VersionConstraint) {
       mismatchDescription.add('was not a VersionConstraint');
       return mismatchDescription;