Use specific messages for const constructor with body.

pkg/dart_messages/lib/shared_messages.dart

 // 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.
 
 // An update to this file must be followed by regenerating the corresponding
 // json, dart2js and analyzer file. Use `publish.dart` in the bin directory.
 //
 // Every message in this file must have an id. Use `message_id.dart` in the
 // bin directory to generate a fresh one.
 
@@ skipping 174 matching lines @@
           'fileA.dart': '''
         or a map from file to content.
         again multiline''',
           'fileB.dart': '''
         with possibly multiple files.
         muliline too'''
         }
       ]),
 
   // Const constructors (factory or not) may not have a body.
   'CONST_CONSTRUCTOR_OR_FACTORY_WITH_BODY': new Message(

[floitsch, 2016/03/08 10:56:52]

As long as we haven't published the messages database, update the file.
That is: delete the entry and reassign the subIds (so they start from 0).
(don't forget to "publish" after the change).

[Johnni Winther, 2016/03/10 08:55:42]

Done.

       id: 'LGJGHW',
       subId: 0,
       categories: [Category.parserError],
       template: "Const constructor or factory can't have a body.",
       howToFix: "Remove the 'const' keyword or the body.",
-      usedBy: [dart2js],
+      usedBy: [],
       examples: const [
         r"""
          class C {
            const C() {}
          }
 
          main() => new C();""",
         r"""
          class C {
            const factory C() {}
          }
 
          main() => new C();"""
       ]),
   // Const constructors may not have a body.
   'CONST_CONSTRUCTOR_WITH_BODY': new Message(
       id: 'LGJGHW',
       subId: 1,
       specializationOf: "CONST_CONSTRUCTOR_OR_FACTORY_WITH_BODY",
       categories: [Category.parserError],
       template: "Const constructor can't have a body.",
       howToFix: "Try removing the 'const' keyword or the body.",
-      usedBy: [analyzer],
+      usedBy: [analyzer, dart2js],
       examples: const [
         r"""
          class C {
            const C() {}
          }
 
          main() => new C();"""
       ]),
   // Const constructor factories may only redirect (and must not have a body).
   'CONST_FACTORY': new Message(
       id: 'LGJGHW',
       subId: 2,
       specializationOf: "CONST_CONSTRUCTOR_OR_FACTORY_WITH_BODY",
       categories: [Category.parserError],
       template: "Only redirecting factory constructors can be declared to "
           "be 'const'.",
       howToFix: "Try removing the 'const' keyword or replacing the body with "
           "'=' followed by a valid target.",
-      usedBy: [analyzer],
+      usedBy: [analyzer, dart2js],
       examples: const [
         r"""
          class C {
            const factory C() {}
          }
 
          main() => new C();"""
       ]),
 
   'EXTRANEOUS_MODIFIER': new Message(
@@ skipping 643 matching lines @@
         main() { x = 3; }
         """,
         """
         const x = 1;
         main() { x = 3; }
         """,
         "get foo => null  main() { foo = 5; }",
         "const foo = 0  main() { foo = 5; }",
       ]),
 };