Refactor least upper bound computation; support bottom correctly.

pkg/analyzer/test/generated/test_all.dart

Index: pkg/analyzer/test/generated/test_all.dart
diff --git a/pkg/analyzer/test/generated/test_all.dart b/pkg/analyzer/test/generated/test_all.dart
index b632b512395e54bd8815930ca488961b09ded10b..08f5ba34e05672a5918de6103f91f8f1bcb43ba1 100644
--- a/pkg/analyzer/test/generated/test_all.dart
+++ b/pkg/analyzer/test/generated/test_all.dart
@@ -21,6 +21,7 @@ import 'resolver_test.dart' as resolver_test;
 import 'scanner_test.dart' as scanner_test;
 import 'static_type_warning_code_test.dart' as static_type_warning_code_test;
 import 'static_warning_code_test.dart' as static_warning_code_test;
+import 'type_system_test.dart' as type_system_test;
 import 'utilities_test.dart' as utilities_test;
 
 /// Utility for manually running all tests.
@@ -42,6 +43,7 @@ main() {
     scanner_test.main();
     static_type_warning_code_test.main();
     static_warning_code_test.main();
+    type_system_test.main();
     utilities_test.main();
   });
 }