Link to stable-errors site from pub-build messages on the command line.

pkg/polymer/lib/src/build/messages.dart

 // Copyright (c) 2014, 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.
 
 /// Contains all error and warning messages produced by polymer.
 library polymer.src.build.messages;
 
 import 'package:code_transformers/messages/messages.dart';
 import 'constants.dart';
 
@@ skipping 89 matching lines @@
 ''');
 
 const MISSING_HREF = const MessageTemplate(
     const MessageId('polymer', 9),
     'link rel="%-rel-%" missing href.',
     'Missing href on a `<link>` tag',
     'All `<link>` tags should have a valid URL to a resource.');
 
 const ELEMENT_DEPRECATED_EONS_AGO = const MessageTemplate(
     const MessageId('polymer', 10),
-    '<element> elements are not supported, use <polymer-element> instead',
+    '<element> elements are not supported, use <polymer-element> instead.',
     '`<element>` is deprecated',
     '''
 Long ago `<polymer-element>` used to be called `<element>`. You probably ran
 into this error if you were migrating code that was written on a very early
 version of polymer.
 ''');
 
 // TODO(jmesserly): this warning is wrong if someone is using raw custom
 // elements. Is there another way we can handle this warning that won't
 // generate false positives?
@@ skipping 411 matching lines @@
     'Custom element found in document body without an '
     '"unresolved" attribute on it or one of its parents. This means '
     'your app probably has a flash of unstyled content before it '
     'finishes loading.',
     'Possible flash of unstyled content',
     '''
 Custom element found in document body without an "unresolved" attribute on it or
 one of its parents. This means your app probably has a flash of unstyled content
 before it finishes loading. See <http://goo.gl/iN03Pj> for more info.
 ''');