report const class as a more specific error code

pkg/front_end/lib/src/fasta/fasta_codes_generated.dart

 // Copyright (c) 2017, 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.
 
 // NOTE: THIS FILE IS GENERATED. DO NOT EDIT.
 //
 // Instead modify 'pkg/front_end/messages.yaml' and run
 // 'pkg/front_end/tool/_fasta/generate_messages.dart' to update.
 
 part of fasta.codes;
@@ skipping 347 matching lines @@
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Code<Null> codeConflictsWithTypeVariableCause =
     messageConflictsWithTypeVariableCause;
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const MessageCode messageConflictsWithTypeVariableCause = const MessageCode(
     "ConflictsWithTypeVariableCause",
     message: r"""This is the type variable.""");
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Null> codeConstClass = messageConstClass;
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const MessageCode messageConstClass = const MessageCode("ConstClass",
+    analyzerCode: "CONST_CLASS",
+    dart2jsCode: "EXTRANEOUS_MODIFIER",
+    message: r"""Classes can't be declared to be 'const'.""",
+    tip:
+        r"""Try removing the 'const' keyword. If you're trying to indicate that instances of the class can be constants, place the 'const' keyword on  the class' constructor(s).""");
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Code<Null> codeConstConstructorNonFinalField =
     messageConstConstructorNonFinalField;
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const MessageCode messageConstConstructorNonFinalField = const MessageCode(
     "ConstConstructorNonFinalField",
     message: r"""Constructor is marked 'const' so all fields must be final.""");
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Code<Null> codeConstConstructorNonFinalFieldCause =
@@ skipping 2741 matching lines @@
         r"""'yield' can't be used as an identifier in 'async', 'async*', or 'sync*' methods.""");
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Code<Null> codeYieldNotGenerator = messageYieldNotGenerator;
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const MessageCode messageYieldNotGenerator = const MessageCode(
     "YieldNotGenerator",
     dart2jsCode: "*ignored*",
     message: r"""'yield' can only be used in 'sync*' or 'async*' methods.""");