Use common.dart to re-export commonly used entities.

pkg/compiler/lib/src/cps_ir/cps_ir_nodes_sexpr.dart

 // Copyright (c) 2014, 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.ir_nodes_sexpr;
 
 import '../constants/values.dart';
 import '../util/util.dart';
 import 'cps_ir_nodes.dart';
 import '../universe/call_structure.dart' show
     CallStructure;
-import '../universe/selector.dart' show
-    Selector;
 
 /// A [Decorator] is a function used by [SExpressionStringifier] to augment the
 /// output produced for a node or reference.  It can be provided to the
 /// constructor.
 typedef String Decorator(node, String s);
 
 /// Generate a Lisp-like S-expression representation of an IR node as a string.
 class SExpressionStringifier extends Indentation implements Visitor<String> {
   final _Namer namer = new _Namer();
 
@@ skipping 469 matching lines @@
   void setReturnContinuation(Continuation node) {
     assert(!_names.containsKey(node) || _names[node] == 'return');
     _names[node] = 'return';
   }
 
   String getName(Node node) {
     if (!_names.containsKey(node)) return 'MISSING_NAME';
     return _names[node];
   }
 }