Move continueWithExpression to IrBuilder.

sdk/lib/_internal/compiler/implementation/cps_ir/cps_ir_tracer.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_tracer;
 
 import 'dart:async' show EventSink;
 
 import 'cps_ir_nodes.dart' as cps_ir hide Function;
 import '../tracer.dart';
@@ skipping 148 matching lines @@
     for (cps_ir.LiteralMapEntry entry in node.entries) {
       String key = formatReference(entry.key);
       String value = formatReference(entry.value);
       entries.add("$key: $value");
     }
     printStmt(dummy, "LiteralMap (${entries.join(', ')})");
   }
 
   visitTypeOperator(cps_ir.TypeOperator node) {
     String dummy = names.name(node);
-    String operator = node.operator;
+    String operator = node.isTypeTest ? 'is' : 'as';
     List<String> entries = new List<String>();
     String receiver = formatReference(node.receiver);
     printStmt(dummy, "TypeOperator ($operator $receiver ${node.type})");
   }
 
   visitInvokeContinuation(cps_ir.InvokeContinuation node) {
     String dummy = names.name(node);
     String kont = formatReference(node.continuation);
     String args = node.arguments.map(formatReference).join(', ');
     printStmt(dummy, "InvokeContinuation $kont ($args)");
@@ skipping 203 matching lines @@
     }
   }
 
   visitContinuation(cps_ir.Continuation c) {
     var old_node = current_block;
     current_block = getBlock(c);
     visit(c.body);
     current_block = old_node;
   }
 }