dart2js cps: Make Identical a built-in and add Interceptor to Tree IR.

pkg/compiler/lib/src/tree_ir/tree_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 tree_ir_tracer;
 
 import 'dart:async' show EventSink;
 import '../tracer.dart';
 import 'tree_ir_nodes.dart';
 
@@ skipping 497 matching lines @@
     return node.dartType.toString();
   }
 
   @override
   String visitCreateInvocationMirror(CreateInvocationMirror node) {
     String args = node.arguments.map(visitExpression).join(', ');
     return 'CreateInvocationMirror(${node.selector.name}, $args)';
   }
 
   @override
+  String visitInterceptor(Interceptor node) {
+    return 'Interceptor(${visitExpression(node.input)})';
+  }
+
+  @override
   String visitForeignExpression(ForeignExpression node) {
     String arguments = node.arguments.map(visitExpression).join(', ');
     return 'Foreign "${node.codeTemplate}"($arguments)';
   }
 
   @override
   String visitApplyBuiltinOperator(ApplyBuiltinOperator node) {
     String args = node.arguments.map(visitExpression).join(', ');
     return 'ApplyBuiltinOperator ${node.operator} ($args)';
   }
@@ skipping 17 matching lines @@
       String prefix = v.element == null ? 'v' : '${v.element.name}_';
       while (name == null || _usedNames.contains(name)) {
         name = "$prefix${_counter++}";
       }
       _names[v] = name;
       _usedNames.add(name);
     }
     return name;
   }
 }