Fix pre-existing HintCode.UNNECESSARY_TYPE_CHECK_TRUE (dart-lang/pub_semver#60)

pkgs/pub_semver/test/version_constraint_test.dart

diff --git a/pkgs/pub_semver/test/version_constraint_test.dart b/pkgs/pub_semver/test/version_constraint_test.dart
index 1434cfe..4fbcbe0 100644
--- a/pkgs/pub_semver/test/version_constraint_test.dart
+++ b/pkgs/pub_semver/test/version_constraint_test.dart
@@ -36,7 +36,6 @@
     test('parses "any"', () {
       var constraint = VersionConstraint.parse('any');
 
-      expect(constraint is VersionConstraint, isTrue);
       expect(
           constraint,
           allows(Version.parse('0.0.0'), Version.parse('1.2.3'),