dart2js: Remove oldEmitter field in emitter-task.

tests/compiler/dart2js/mirrors_used_test.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.
 
 /// Test that the @MirrorsUsed annotation suppress hints and that only
 /// requested elements are retained for reflection.
 library dart2js.test.mirrors_used_test;
 
 import 'package:expect/expect.dart';
 import "package:async_helper/async_helper.dart";
@@ skipping 71 matching lines @@
     List<Element> nativeClasses = [
           compiler.intClass, compiler.doubleClass, compiler.numClass,
           compiler.stringClass, compiler.boolClass, compiler.nullClass,
           compiler.listClass
         ];
     JavaScriptBackend backend = compiler.backend;
     Iterable<String> nativeNames = nativeClasses.map(backend.namer.className);
     expectedNames = expectedNames.map(backend.namer.asName).toList();
     expectedNames.addAll(nativeNames);
 
+    // Mirrors only work in the full emitter. We can thus be certain that the
+    // emitter is the full emitter.
+    OldEmitter fullEmitter = backend.emitter.emitter;
     Set recordedNames = new Set()
-        ..addAll(backend.emitter.oldEmitter.recordedMangledNames)
-        ..addAll(backend.emitter.oldEmitter.mangledFieldNames.keys)
-        ..addAll(backend.emitter.oldEmitter.mangledGlobalFieldNames.keys);
+        ..addAll(fullEmitter.recordedMangledNames)
+        ..addAll(fullEmitter.mangledFieldNames.keys)
+        ..addAll(fullEmitter.mangledGlobalFieldNames.keys);
     Expect.setEquals(new Set.from(expectedNames), recordedNames);
 
     for (var library in compiler.libraryLoader.libraries) {
       library.forEachLocalMember((member) {
         if (library == compiler.mainApp && member.name == 'Foo') {
           Expect.isTrue(
               compiler.backend.isAccessibleByReflection(member), '$member');
           member.forEachLocalMember((classMember) {
             Expect.isTrue(
                 compiler.backend.isAccessibleByReflection(classMember),
@@ skipping 60 matching lines @@
 library lib;
 
 import 'dart:mirrors';
 
 useReflect(type) {
   print(new Symbol('Foo'));
   print(MirrorSystem.getName(reflectClass(type).owner.qualifiedName));
 }
 """,
 };