dart2js cps: Type casts and related changes to type propagation.

pkg/compiler/lib/src/js_backend/backend.dart

 // Copyright (c) 2012, 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.
 
 part of js_backend;
 
 const VERBOSE_OPTIMIZER_HINTS = false;
 
 class JavaScriptItemCompilationContext extends ItemCompilationContext {
   final Set<HInstruction> boundsChecked = new Set<HInstruction>();
@@ skipping 1748 matching lines @@
   }
 
   Element getCheckSubtype() {
     return findHelper('checkSubtype');
   }
 
   Element getAssertSubtype() {
     return findHelper('assertSubtype');
   }
 
+  Element getSubtypeCast() {
+    return findHelper('subtypeCast');
+  }
+
   Element getCheckSubtypeOfRuntimeType() {
     return findHelper('checkSubtypeOfRuntimeType');
   }
 
+  Element getAssertSubtypeOfRuntimeType() {
+    return findHelper('assertSubtypeOfRuntimeType');
+  }
+
+  Element getSubtypeOfRuntimeTypeCast() {
+    return findHelper('subtypeOfRuntimeTypeCast');
+  }
+
   Element getCheckDeferredIsLoaded() {
     return findHelper('checkDeferredIsLoaded');
   }
 
-  Element getAssertSubtypeOfRuntimeType() {
-    return findHelper('assertSubtypeOfRuntimeType');
-  }
-
   Element getThrowNoSuchMethod() {
     return findHelper('throwNoSuchMethod');
   }
 
   Element getCreateRuntimeType() {
     return findHelper('createRuntimeType');
   }
 
   Element getFallThroughError() {
     return findHelper("getFallThroughError");
@@ skipping 1160 matching lines @@
   }
 }
 
 /// Records that [constant] is used by the element behind [registry].
 class Dependency {
   final ConstantValue constant;
   final Element annotatedElement;
 
   const Dependency(this.constant, this.annotatedElement);
 }