Fix type warnings and a few other warnings, and probably even an error.

lib/compiler/implementation/ssa/tracer.dart

 // Copyright (c) 2011, 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('tracer');
 
 #import('dart:io');
 #import('ssa.dart');
 #import('../leg.dart');
 
@@ skipping 401 matching lines @@
       case HType.NUMBER: type = "number"; break;
       case HType.STRING: type = "string"; break;
       case HType.STRING_OR_ARRAY: type = "string_or_array"; break;
       case HType.UNKNOWN: type = 'unknown'; break;
       default: unreachable();
     }
     return "TypeGuard: ${temporaryId(node.inputs[0])} is $type";
   }
 
   String visitIs(HIs node) {
-    String type = node.typeExpression.toString();
+    String type = node.typeName.toString();
     return "TypeTest: ${temporaryId(node.expression)} is $type";
   }
 }