After a dynamic call, refine the receiver type by looking at the potential targets of that call.

tests/compiler/dart2js/dead_bailout_target_test.dart

 // Copyright (c) 2013, 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.
 
 // This unit test of dart2js checks that a SSA bailout target
 // instruction gets removed from the graph when it's not used.
 
 import "package:expect/expect.dart";
 import 'compiler_helper.dart';
 
@@ skipping 42 matching lines @@
   
   // Check that the foo bailout method is generated.
   checkNumberOfMatches(
       new RegExp('foo\\\$bailout').allMatches(generated).iterator, 2);
 
   // Check that it's the only bailout method.
   checkNumberOfMatches(new RegExp('bailout').allMatches(generated).iterator, 2);
 
   // Check that the bailout method has a case 2 for the state, which
   // is the second bailout in foo.
-  RegExp state = new RegExp('case 2:[ \n]+state0 = 0;');
+  RegExp state = new RegExp('case 2:');
   checkNumberOfMatches(state.allMatches(generated).iterator, 1);
 
   // Finally, make sure that the reason foo does not contain
   // 'getInterceptor' is not because the compiler renamed it.
   Expect.isTrue(generated.contains('getInterceptor'));
 }