Print the location of duplicated elements.

dart/sdk/lib/_internal/compiler/implementation/compiler.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.
 
 part of dart2js;
 
 /**
  * If true, print a warning for each method that was resolved, but not
  * compiled.
  */
@@ skipping 1076 matching lines @@
   }
 
   // TODO(ahe): Rename to reportWarning when that method has been removed.
   void reportWarningCode(Spannable node, MessageKind errorCode,
                          [Map arguments = const {}]) {
     reportMessage(spanFromSpannable(node),
                   errorCode.error(arguments),
                   api.Diagnostic.WARNING);
   }
 
+  void reportInfo(Spannable node, MessageKind errorCode,
+                  [Map arguments = const {}]) {
+    reportMessage(spanFromSpannable(node),
+                  errorCode.error(arguments),
+                  api.Diagnostic.INFO);
+  }
+
   void reportMessage(SourceSpan span, Diagnostic message, api.Diagnostic kind) {
     // TODO(ahe): The names Diagnostic and api.Diagnostic are in
     // conflict. Fix it.
     reportDiagnostic(span, "$message", kind);
   }
 
   /// Returns true if a diagnostic was emitted.
   bool onDeprecatedFeature(Spannable span, String feature) {
     if (currentElement == null)
       throw new SpannableAssertionFailure(span, feature);
@@ skipping 256 matching lines @@
 
   void close() {}
 
   toString() => name;
 
   /// Convenience method for getting an [api.CompilerOutputProvider].
   static NullSink outputProvider(String name, String extension) {
     return new NullSink('$name.$extension');
   }
 }