dart2js cps: Backward redundant null check removal

pkg/compiler/lib/src/common/names.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 containing identifier, names, and selectors commonly used through
 /// the compiler.
 library dart2js.common.names;
 
 import '../elements/elements.dart' show
     Name,
@@ skipping 54 matching lines @@
   static const Name noSuchMethod_ = const PublicName(Identifiers.noSuchMethod_);
 
   /// The name of the to-string method on 'Object'.
   static const Name toString_ = const PublicName('toString');
 
   static const Name INDEX_NAME = const PublicName("[]");
   static const Name INDEX_SET_NAME = const PublicName("[]=");
   static const Name CALL_NAME = Names.call;
 
   static const Name length = const PublicName(Identifiers.length);
+
+  static const Name runtimeType_ = const PublicName(Identifiers.runtimeType_);
 }
 
 /// [Selector]s commonly used.
 class Selectors {
   /// The selector for calling the cancel method on 'StreamIterator'.
   static final Selector cancel =
       new Selector.call(const PublicName('cancel'), CallStructure.NO_ARGS);
 
   /// The selector for getting the current element property used in for-each
   /// loops.
@@ skipping 22 matching lines @@
 
   static final Selector equals = new Selector.binaryOperator('==');
 
   static final Selector length = new Selector.getter(Names.length);
 
   static final Selector codeUnitAt =
       new Selector.call(const PublicName('codeUnitAt'), CallStructure.ONE_ARG);
 
   static final Selector index = new Selector.index();
 
+  static final Selector runtimeType_ = new Selector.getter(Names.runtimeType_);
+
   /// List of all the selectors held in static fields.
   ///
   /// These objects are shared between different runs in batch-mode and must
   /// thus remain in the [Selector.canonicalizedValues] map.
   static final List<Selector> ALL = <Selector>[
       cancel, current, iterator, moveNext, noSuchMethod_, toString_,
-      hashCode_, compareTo, equals, length, codeUnitAt, index];
+      hashCode_, compareTo, equals, length, codeUnitAt, index, runtimeType_];
 }
 
 /// [Uri]s commonly used.
 class Uris {
   /// The URI for 'dart:async'.
   static final Uri dart_async = new Uri(scheme: 'dart', path: 'async');
 
   /// The URI for 'dart:core'.
   static final Uri dart_core = new Uri(scheme: 'dart', path: 'core');
 
   /// The URI for 'dart:html'.
   static final Uri dart_html = new Uri(scheme: 'dart', path: 'html');
 
   /// The URI for 'dart:mirrors'.
   static final Uri dart_mirrors = new Uri(scheme: 'dart', path: 'mirrors');
 
   /// The URI for 'dart:_internal'.
   static final Uri dart__internal = new Uri(scheme: 'dart', path: '_internal');
 
   /// The URI for 'dart:_native_typed_data'.
   static final Uri dart__native_typed_data =
       new Uri(scheme: 'dart', path: '_native_typed_data');
 }