dart2js cps_ir: Use interceptors for is-checks.

pkg/compiler/lib/src/tree_ir/optimization/pull_into_initializers.dart

 // Copyright (c) 2015, 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.optimization.pull_into_initializers;
 
 import 'optimization.dart' show Pass;
 import '../tree_ir_nodes.dart';
 
 /// Where a variable has been assigned.
@@ skipping 297 matching lines @@
     ++impureCounter;
     return node;
   }
 
   Expression visitSetStatic(SetStatic node) {
     super.visitSetStatic(node);
     ++impureCounter;
     return node;
   }
 
+  Expression visitGetTypeTestProperty(GetTypeTestProperty node) {
+    super.visitGetTypeTestProperty(node);
+    return node;
+  }
+
   Expression visitGetLength(GetLength node) {
     super.visitGetLength(node);
     ++impureCounter;
     return node;
   }
 
   Expression visitGetIndex(GetIndex node) {
     super.visitGetIndex(node);
     ++impureCounter;
     return node;
@@ skipping 32 matching lines @@
 
   @override
   Expression visitForeignExpression(ForeignExpression node) {
     rewriteList(node.arguments);
     if (node.nativeBehavior.sideEffects.hasSideEffects()) {
       ++impureCounter;
     }
     return node;
   }
 }