dart2dart Preproces placeholders instead of renaming them lazily,

lib/compiler/implementation/dart_backend/backend.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 DartBackend extends Backend {
   final List<CompilerTask> tasks;
   final UnparseValidator unparseValidator;
 
   Map<Element, TreeElements> get resolvedElements() =>
       compiler.enqueuer.resolution.resolvedElements;
@@ skipping 57 matching lines @@
       new ReferencedElementCollector(
           compiler, element, treeElements, typedefs, classes)
       .collect();
     });
     final emptyTreeElements = new TreeElementMapping();
     collectElement(element) { collector.collect(element, emptyTreeElements); }
     typedefs.forEach(collectElement);
     classes.forEach(collectElement);
 
     ConflictingRenamer renamer =
-        new ConflictingRenamer(compiler, collector.placeholders);
+        new ConflictingRenamer(compiler, collector);
     Emitter emitter = new Emitter(compiler, renamer);
     resolvedElements.forEach((element, treeElements) {
       if (!shouldOutput(element)) return;
       if (element.isMember()) {
         ClassElement enclosingClass = element.getEnclosingClass();
         assert(enclosingClass.isClass());
         assert(enclosingClass.isTopLevel());
         addMemberToClass(element, enclosingClass);
         return;
       }
@@ skipping 73 matching lines @@
     }
     typeAnnotation.visitChildren(this);
   }
 
   void collect() {
     compiler.withCurrentElement(rootElement, () {
       rootElement.parseNode(compiler).accept(this);
     });
   }
 }