Revert "Move dart2jslib parts into separate 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 '../elements/elements.dart';
 import '../dart2jslib.dart';
 import '../dart_types.dart';
 import '../types/types.dart';
 import '../tree/tree.dart';
 import '../util/util.dart';
-import '../world.dart' show
-    ClassWorld,
-    World;
 
 part 'function_set.dart';
 part 'side_effects.dart';
 
 class UniverseSelector {
   final Selector selector;
   final TypeMask mask;
 
   UniverseSelector(this.selector, this.mask);
 
@@ skipping 876 matching lines @@
     // Add bits from the call structure.
     return Hashing.mixHashCodeBits(hash, callStructure.hashCode);
   }
 
   String toString() {
     return 'Selector($kind, $name, ${callStructure.structureToString()})';
   }
 
   Selector toCallSelector() => new Selector.callClosureFrom(this);
 }