Use the constant system to do a subtype type in the compile time constant handler. This is needed b…

sdk/lib/_internal/compiler/implementation/compile_time_constants.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 dart2js;
 
 /**
  * The [ConstantHandler] keeps track of compile-time constants,
  * initializations of global and static fields, and default values of
  * optional parameters.
@@ skipping 116 matching lines @@
         value = new NullConstant();
       } else {
         Node right = assignment.arguments.head;
         value =
             compileNodeWithDefinitions(right, definitions, isConst: isConst);
         if (compiler.enableTypeAssertions
             && value != null
             && element.isField()) {
           DartType elementType = element.computeType(compiler);
           DartType constantType = value.computeType(compiler);
-          if (!compiler.types.isSubtype(constantType, elementType)) {
+          if (!constantSystem.isSubtype(compiler, constantType, elementType)) {
             if (isConst) {
               MessageKind kind = MessageKind.NOT_ASSIGNABLE;
               compiler.reportError(node, new CompileTimeConstantError(
                   kind, [elementType, constantType]));
             } else {
               // If the field can be lazily initialized, we will throw
               // the exception at runtime.
               value = null;
             }
           }
@@ skipping 675 matching lines @@
             // Use the default value.
             fieldValue = compiler.compileConstant(field);
           }
           jsNewArguments.add(fieldValue);
         },
         includeBackendMembers: true,
         includeSuperMembers: true);
     return jsNewArguments;
   }
 }