Make the universe parts into small libraries.

pkg/compiler/lib/src/js_backend/lookup_map_analysis.dart

 // Copyright (c) 2015, 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.
 
 /// Analysis to determine how to generate code for `LookupMap`s.
 library compiler.src.js_backend.lookup_map_analysis;
 
 import '../common/registry.dart' show Registry;
 import '../compiler.dart' show Compiler;
 import '../diagnostics/messages.dart' show MessageKind;
 import '../constants/values.dart' show
      ConstantValue,
      ConstructedConstantValue,
      ListConstantValue,
      NullConstantValue,
      StringConstantValue,
      TypeConstantValue;
 import '../dart_types.dart' show DartType;
 import '../elements/elements.dart' show
     ClassElement,
     Element,
     Elements,
     FieldElement,
     FunctionElement,
     FunctionSignature,
     LibraryElement,
     VariableElement;
-import '../enqueue.dart' show Enqueuer;
 import 'js_backend.dart' show JavaScriptBackend;
 import '../dart_types.dart' show DynamicType, InterfaceType;
 import 'package:pub_semver/pub_semver.dart';
 
 /// An analysis and optimization to remove unused entries from a `LookupMap`.
 ///
 /// `LookupMaps` are defined in `package:lookup_map/lookup_map.dart`. They are
 /// simple maps that contain constant expressions as keys, and that only support
 /// the lookup operation.
 ///
@@ skipping 392 matching lines @@
       }
     } else {
       original.fields[analysis.entriesField] =
           new ListConstantValue(listType, keyValuePairs);
     }
   }
 }
 
 final _validLookupMapVersionConstraint =
     new VersionConstraint.parse('^0.0.1');