Make the universe parts into small libraries.

pkg/compiler/lib/src/resolution/send_resolver.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.
 
 library dart2js.semantics_visitor.resolver;
 
 import '../constants/expressions.dart';
 import '../dart_types.dart';
 import '../diagnostics/messages.dart' show
     MessageKind;
 import '../diagnostics/spannable.dart' show
     Spannable,
     SpannableAssertionFailure;
 import '../elements/elements.dart';
 import '../tree/tree.dart';
-import '../universe/universe.dart';
+import '../universe/call_structure.dart' show
+    CallStructure;
+import '../universe/selector.dart' show
+    Selector;
 
 import 'access_semantics.dart';
 import 'semantic_visitor.dart';
 import 'send_structure.dart';
 import 'tree_elements.dart';
 
 abstract class SendResolverMixin {
   TreeElements get elements;
 
   internalError(Spannable spannable, String message);
@@ skipping 442 matching lines @@
       return internalError(node, "Unexpected variable $element.");
     }
     if (element.isConst) {
       ConstantExpression constant = elements.getConstant(element.initializer);
       return new ConstantVariableStructure(kind, node, element, constant);
     } else {
       return new NonConstantVariableStructure(kind, node, element);
     }
   }
 }