Add TypeVariable object on runtime to support reflection on type variables.

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 617 matching lines @@
     InterfaceType type = elements.getType(node);
     List<Constant> evaluateArguments(FunctionElement constructor) {
       Selector selector = elements.getSelector(send);
       return evaluateArgumentsToConstructor(
           node, selector, send.arguments, constructor);
     }
     return makeConstructedConstant(node, type, constructor, evaluateArguments);
   }
 
   Constant makeConstructedConstant(
-      Node node, InterfaceType type, FunctionElement constructor,
+      Spannable node, InterfaceType type, FunctionElement constructor,
       List<Constant> getArguments(FunctionElement constructor)) {
     if (constructor.isRedirectingFactory) {
       type = constructor.computeTargetType(compiler, type);
     }
 
     // The redirection chain of this element may not have been resolved through
     // a post-process action, so we have to make sure it is done here.
     compiler.resolver.resolveRedirectionChain(constructor, node);
     constructor = constructor.redirectionTarget;
     ClassElement classElement = constructor.getEnclosingClass();
@@ skipping 229 matching lines @@
           if (fieldValue == null) {
             // Use the default value.
             fieldValue = handler.compileConstant(field);
           }
           jsNewArguments.add(fieldValue);
         },
         includeSuperAndInjectedMembers: true);
     return jsNewArguments;
   }
 }