Make the universe parts into small libraries.

pkg/compiler/lib/src/universe/universe.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library universe;
 
 import 'dart:collection';
 
 import '../common/names.dart' show
     Identifiers,
     Names,
     Selectors;
 import '../compiler.dart' show
     Compiler;
 import '../diagnostics/invariant.dart' show
     invariant;
 import '../diagnostics/spannable.dart' show
     SpannableAssertionFailure;
 import '../elements/elements.dart';
 import '../dart_types.dart';
 import '../tree/tree.dart';
 import '../types/types.dart';
 import '../util/util.dart';
 import '../world.dart' show
     ClassWorld,
     World;
 
-part 'call_structure.dart';
-part 'function_set.dart';
-part 'selector.dart';
-part 'side_effects.dart';
+import 'call_structure.dart';
+import 'selector.dart' show
+    Selector;
+import 'function_set.dart';
+import 'side_effects.dart';
 
 class UniverseSelector {
   final Selector selector;
   final ReceiverMask mask;
 
   UniverseSelector(this.selector, this.mask);
 
   bool appliesUnnamed(Element element, ClassWorld world) {
     return selector.appliesUnnamed(element, world) &&
         (mask == null || mask.canHit(element, selector, world));
@@ skipping 324 matching lines @@
   // TODO(ahe): Replace this method with something that is O(1), for example,
   // by using a map.
   List<LocalFunctionElement> slowDirectlyNestedClosures(Element element) {
     // Return new list to guard against concurrent modifications.
     return new List<LocalFunctionElement>.from(
         allClosures.where((LocalFunctionElement closure) {
           return closure.executableContext == element;
         }));
   }
 }