Use specific messages for const constructor with body.

pkg/compiler/lib/src/resolution/resolution.dart

 // Copyright (c) 2012, 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.resolution;
 
 import 'dart:collection' show Queue;
 
 import '../common.dart';
 import '../common/names.dart' show
@@ skipping 206 matching lines @@
     while (classElement != null) {
       if (compiler.backend.isNative(classElement)) return true;
       classElement = classElement.superclass;
     }
     return false;
   }
 
   WorldImpact resolveMethodElementImplementation(
       FunctionElement element, FunctionExpression tree) {
     return reporter.withCurrentElement(element, () {
-      if (element.isExternal && tree.hasBody()) {
+      if (element.isExternal && tree.hasBody) {
         reporter.reportErrorMessage(
             element,
             MessageKind.EXTERNAL_WITH_BODY,
             {'functionName': element.name});
       }
       if (element.isConstructor) {
         if (tree.returnType != null) {
           reporter.reportErrorMessage(
               tree, MessageKind.CONSTRUCTOR_WITH_RETURN_TYPE);
         }
-        if (element.isConst &&
-            tree.hasBody() &&
-            !tree.isRedirectingFactory) {
-          reporter.reportErrorMessage(
-              tree, MessageKind.CONST_CONSTRUCTOR_OR_FACTORY_WITH_BODY);
+        if (tree.hasBody && element.isConst) {
+          if (element.isGenerativeConstructor) {
+            reporter.reportErrorMessage(
+                tree, MessageKind.CONST_CONSTRUCTOR_WITH_BODY);
+          } else if (!tree.isRedirectingFactory) {
+            reporter.reportErrorMessage(
+                tree, MessageKind.CONST_FACTORY);
+          }
         }
       }
 
       ResolverVisitor visitor = visitorFor(element);
       ResolutionRegistry registry = visitor.registry;
       registry.defineFunction(tree, element);
       visitor.setupFunction(tree, element);
       processAsyncMarker(compiler, element, registry);
 
       if (element.isGenerativeConstructor) {
@@ skipping 874 matching lines @@
   TreeElements get treeElements {
     assert(invariant(this, _treeElements !=null,
         message: "TreeElements have not been computed for $this."));
     return _treeElements;
   }
 
   void reuseElement() {
     _treeElements = null;
   }
 }