Remove scanBuiltinLibraries.

sdk/lib/_internal/compiler/implementation/mirror_renamer/renamer.dart

 // Copyright (c) 2013, 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 mirror_renamer;
 
 class MirrorRenamer {
   static const String MIRROR_HELPER_GET_NAME_FUNCTION = 'helperGetName';
-  static const String MIRROR_HELPER_LIBRARY_NAME = '_mirror_helper';
+  static final Uri DART_MIRROR_HELPER =
+      new Uri(scheme: 'dart', path: '_mirror_helper');
   static const String MIRROR_HELPER_SYMBOLS_MAP_NAME = '_SYMBOLS';
 
   /// Maps mangled name to original name.
   Map<String, String> symbols = new Map<String, String>();
   /// Contains all occurrencs of MirrorSystem.getName() calls in the user code.
   List<Node> mirrorSystemGetNameNodes = <Node>[];
   /**
    *  Initialized when the placeholderCollector collects the FunctionElement
    *  backend.mirrorHelperGetNameFunction which represents the helperGetName
    *  function in _mirror_helper.
@@ skipping 70 matching lines @@
     sb.writeCharCode(0); // Terminate the string with '0', see [StringScanner].
     topLevelNodes.add(parse(sb.toString()));
 
     // Replace calls to Mirrorsystem.getName with calls to helper function.
     mirrorSystemGetNameNodes.forEach((node) {
       renames[node.selector] = renames[mirrorHelperGetNameFunctionNode.name];
       renames[node.receiver] = '';
     });
   }
 }