dart2dart Preproces placeholders instead of renaming them lazily,

lib/compiler/implementation/dart_backend/placeholder.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.
-
-class Placeholder {
-  const Placeholder();
-  abstract String rename(ConflictingRenamer renamer);
-}
-
-class NullPlaceholder extends Placeholder {
-  String rename(ConflictingRenamer renamer) => '';
-  String toString() => 'null_placeholder[]';
-}
-
-class PrivatePlaceholder extends Placeholder {
-  final LibraryElement library;
-  final Identifier node;
-  PrivatePlaceholder(this.library, this.node);
-  String rename(ConflictingRenamer renamer) =>
-      renamer.renamePrivateIdentifier(library, node.source.slowToString());
-  String toString() => 'private_placeholder[node($node), $library]';
-}
-
-class ElementPlaceholder extends Placeholder {
-  final Element element;
-  ElementPlaceholder(this.element);
-  String rename(ConflictingRenamer renamer) => renamer.renameElement(element);
-  String toString() => 'element_placeholder[$element]';
-}
-
-class UnresolvedPlaceholder extends Placeholder {
-  const UnresolvedPlaceholder();
-  String rename(ConflictingRenamer renamer) =>
-      renamer.generateUniqueName('unresolved');
-  String toString() => 'unresolved_placeholder';
-}
-
-class LocalPlaceholder extends Placeholder {
-  final FunctionElement scope;
-  final String identifier;
-  LocalPlaceholder(this.scope, this.identifier);
-
-  String rename(ConflictingRenamer renamer) =>
-      renamer.renameLocalIdentifier(scope, identifier);
-  String toString() =>
-      'local_placeholder[scope($scope), id($identifier)]';
-}