Rename Universe to WorldBuilder.

pkg/compiler/lib/src/js_backend/backend.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 js_backend.backend;
 
 import 'dart:async' show Future;
 
 import 'package:js_runtime/shared/embedded_names.dart' as embeddedNames;
 
@@ skipping 32 matching lines @@
 import '../js/rewrite_async.dart';
 import '../js_emitter/js_emitter.dart' show CodeEmitterTask;
 import '../library_loader.dart' show LibraryLoader, LoadedLibraries;
 import '../native/native.dart' as native;
 import '../ssa/ssa.dart' show SsaFunctionCompiler;
 import '../tree/tree.dart';
 import '../types/types.dart';
 import '../universe/call_structure.dart' show CallStructure;
 import '../universe/feature.dart';
 import '../universe/selector.dart' show Selector;
-import '../universe/universe.dart';
+import '../universe/world_builder.dart';
 import '../universe/use.dart'
     show DynamicUse, StaticUse, StaticUseKind, TypeUse, TypeUseKind;
 import '../universe/world_impact.dart'
     show
         ImpactStrategy,
         ImpactUseCase,
         TransformedWorldImpact,
         WorldImpact,
         WorldImpactBuilder,
         WorldImpactVisitor,
@@ skipping 3201 matching lines @@
   ClassElement get mapImplementation => helpers.mapLiteralClass;
   ClassElement get constMapImplementation => helpers.constMapLiteralClass;
   ClassElement get typeImplementation => helpers.typeLiteralClass;
   ClassElement get boolImplementation => helpers.jsBoolClass;
   ClassElement get nullImplementation => helpers.jsNullClass;
   ClassElement get syncStarIterableImplementation => helpers.syncStarIterable;
   ClassElement get asyncFutureImplementation => helpers.futureImplementation;
   ClassElement get asyncStarStreamImplementation => helpers.controllerStream;
   ClassElement get functionImplementation => helpers.coreClasses.functionClass;
 }