Use specific messages for const constructor with body.

pkg/compiler/lib/src/parser/member_listener.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.
 
 library dart2js.parser.member_listener;
 
 import '../common.dart';
 import '../elements/elements.dart' show
     Element,
     ElementKind,
@@ skipping 80 matching lines @@
         recoverableError(getOrSet, 'illegal modifier');
       }
       memberElement = new PartialConstructorElement(
           name, beginToken, endToken,
           ElementKind.GENERATIVE_CONSTRUCTOR,
           method.modifiers,
           enclosingClass);
     } else {
       memberElement = new PartialFunctionElement(
           name, beginToken, getOrSet, endToken,
-          method.modifiers, enclosingClass, hasBody: method.hasBody());
+          method.modifiers, enclosingClass, hasBody: method.hasBody);
     }
     addMember(memberElement);
   }
 
   void endFactoryMethod(Token beginToken, Token endToken) {
     super.endFactoryMethod(beginToken, endToken);
     FunctionExpression method = popNode();
     pushNode(null);
     String name = getMethodNameHack(method.name);
     Identifier singleIdentifierName = method.name.asIdentifier();
@@ skipping 51 matching lines @@
 
   void endMetadata(Token beginToken, Token periodBeforeName, Token endToken) {
     popNode(); // Discard arguments.
     if (periodBeforeName != null) {
       popNode(); // Discard name.
     }
     popNode(); // Discard node (Send or Identifier).
     pushMetadata(new PartialMetadataAnnotation(beginToken, endToken));
   }
 }