sdk files reorganization to make dart2js a proper package

pkg/compiler/lib/src/warnings.dart

 // Copyright (c) 2011, 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;
 
 const DONT_KNOW_HOW_TO_FIX = "Computer says no!";
 
 /**
  * The messages in this file should meet the following guide lines:
@@ skipping 2186 matching lines @@
 
   static const MessageKind HIDDEN_WARNINGS = const MessageKind(
       "#{warnings} warning(s) suppressed in #{uri}.");
 
   static const MessageKind HIDDEN_HINTS = const MessageKind(
       "#{hints} hint(s) suppressed in #{uri}.");
 
   static const MessageKind PREAMBLE = const MessageKind(
     "When run on the command-line, the compiled output might"
     " require a preamble file located in:\n"
-    "  <sdk>/lib/_internal/compiler/js_lib/preambles.");
+    "  <sdk>/lib/_internal/js_runtime/lib/preambles.");
 
   static const MessageKind INVALID_SYNC_MODIFIER = const MessageKind(
       "Invalid modifier 'sync'.",
       options: const ['--enable-async'],
       howToFix: "Try replacing 'sync' with 'sync*'.",
       examples: const [
         "main() sync {}"
       ]);
 
   static const MessageKind INVALID_AWAIT_FOR = const MessageKind(
@@ skipping 395 matching lines @@
   static String convertToString(value) {
     if (value is ErrorToken) {
       // Shouldn't happen.
       return value.assertionMessage;
     } else if (value is Token) {
       value = value.value;
     }
     return '$value';
   }
 }