Attempt to instantiate an enum class is a compile-time error.

pkg/front_end/lib/src/fasta/kernel/body_builder.dart

 // Copyright (c) 2016, 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.
 
 library fasta.body_builder;
 
 import '../fasta_codes.dart'
     show
         FastaMessage,
         codeConstFieldWithoutInitializer,
@@ skipping 2133 matching lines @@
         return;
       }
 
       if (typeArguments != null) {
         assert(arguments.types.isEmpty);
         KernelArguments.setExplicitArgumentTypes(arguments, typeArguments);
       }
 
       String errorName;
       if (type is ClassBuilder) {
+        if (type is EnumBuilder) {
+          push(buildCompileTimeError(
+              "An enum class can't be instantiated.", nameToken.charOffset));
+          return;
+        }
         Builder b =
             type.findConstructorOrFactory(name, token.charOffset, uri, library);
         Member target;
         Member initialTarget;
         if (b == null) {
           // Not found. Reported below.
         } else if (b.isConstructor) {
           initialTarget = b.target;
           if (type.isAbstract) {
             push(evaluateArgumentsBefore(
@@ skipping 1400 matching lines @@
     if (starToken == null) {
       return AsyncMarker.Async;
     } else {
       assert(identical(starToken.stringValue, "*"));
       return AsyncMarker.AsyncStar;
     }
   } else {
     return internalError("Unknown async modifier: $asyncToken");
   }
 }