Make the universe parts into small libraries.

pkg/compiler/lib/src/types/types.dart

Index: pkg/compiler/lib/src/types/types.dart
diff --git a/pkg/compiler/lib/src/types/types.dart b/pkg/compiler/lib/src/types/types.dart
index a06404b12d2db3c3c5229b693da3f3346aa49c61..46be57d2013c601b3a9f9d90493dcff8b7376bc7 100644
--- a/pkg/compiler/lib/src/types/types.dart
+++ b/pkg/compiler/lib/src/types/types.dart
@@ -15,11 +15,19 @@ import '../diagnostics/invariant.dart' show
 import '../diagnostics/spannable.dart' show
     NO_LOCATION_SPANNABLE;
 import '../elements/elements.dart';
-import '../inferrer/concrete_types_inferrer.dart' show ConcreteTypesInferrer;
-import '../inferrer/type_graph_inferrer.dart' show TypeGraphInferrer;
+import '../inferrer/concrete_types_inferrer.dart' show
+    ConcreteTypesInferrer;
+import '../inferrer/type_graph_inferrer.dart' show
+    TypeGraphInferrer;
 import '../tree/tree.dart';
 import '../util/util.dart';
-import '../universe/universe.dart';
+import '../universe/selector.dart' show
+    Selector;
+import '../universe/universe.dart' show
+    ReceiverMask,
+    ReceiverMaskSet,
+    UniverseReceiverMaskSet,
+    ReceiverMaskStrategy;
 import '../world.dart' show
     ClassWorld,
     World;