Support dynamic as type literal.

sdk/lib/_internal/compiler/implementation/js_backend/namer.dart

 // Copyright (c) 2011, 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;
 
 /**
  * Assigns JavaScript identifiers to Dart variables, class-names and members.
  */
 class Namer implements ClosureNamer {
@@ skipping 639 matching lines @@
         name = '$unminifiedName$level';
       }
       name = getMappedInstanceName(name);
     }
     bailoutNames[element] = name;
     return name;
   }
 
   /// Returns the runtime name for [element].  The result is not safe as an id.
   String getRuntimeTypeName(Element element) {
+    if (identical(element, compiler.dynamicClass)) return 'dynamic';
     JavaScriptBackend backend = compiler.backend;
     element = backend.getImplementationClass(element);
     String name = getPrimitiveInterceptorRuntimeName(element);
     return name != null ? name : getName(element);
   }
 
   /**
    * Return a string to be used as the runtime name of this class (instead of
    * the class name) or [null] if the class name should be used.
    */
@@ skipping 609 matching lines @@
         if (!first) {
           sb.write('_');
         }
         sb.write('_');
         visit(link.head);
         first = true;
       }
     }
   }
 }