Allow S->T <: dynamic->T

lib/runtime/dart_runtime.js

 // 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.
 
 // TODO(jmesserly, sigmund): remove these two lines:
 var math = Math;
 var core = core || {int: { parse: Number }, print: e => console.log(e) };
 
 var dart;
 (function (dart) {
@@ skipping 93 matching lines @@
     return obj;
   }
   dart.as = as_;
 
   function is(obj, type) {
     // TODO(vsm): Implement.
     throw new core.UnimplementedError();
   }
   dart.is = is;
 
+  function closureWrap(obj, type) {
+    // TODO(vsm): Remove this once we handle in the checker.
+    return obj;
+  }
+
   function isGroundType(type) {
     // TODO(vsm): Implement.
     throw new core.UnimplementedError();
   }
   dart.isGroundType = isGroundType;
 
   function arity(f) {
     // TODO(vsm): Implement.
     throw new core.UnimplementedError();
   }
@@ skipping 228 matching lines @@
     var init = this[name];
     var result = void 0;
     if (init) result = init.apply(this, arguments);
     return result === void 0 ? this : result;
   };
   // The initializer for Object
   core.Object.prototype.Object = function() {};
   core.Object.prototype.constructor = core.Object;
 
 })(dart || (dart = {}));