Create ResolutionEnqueuer after library loading.

tests/compiler/dart2js/kernel/closed_world_test.dart

 // Copyright (c) 2016, 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.
 
 // Tests that the closed world computed from [WorldImpact]s derived from kernel
 // is equivalent to the original computed from resolution.
 library dart2js.kernel.closed_world_test;
 
 import 'package:async_helper/async_helper.dart';
 import 'package:compiler/src/commandline_options.dart';
@@ skipping 59 matching lines @@
   asyncTest(() async {
     enableDebugMode();
     Compiler compiler = compilerFor(
         entryPoint: entryPoint,
         memorySourceFiles: memorySourceFiles,
         options: [
           Flags.analyzeOnly,
           Flags.useKernel,
           Flags.enableAssertMessage
         ]);
-    ElementResolutionWorldBuilder worldBuilder =
-        compiler.enqueuer.resolution.worldBuilder;
-    worldBuilder.useInstantiationMap = true;
+    ElementResolutionWorldBuilder.useInstantiationMap = true;
     compiler.resolution.retainCachesForTesting = true;
     await compiler.run(entryPoint);
     compiler.resolutionWorldBuilder.closeWorld(compiler.reporter);
 
     JavaScriptBackend backend = compiler.backend;
     // Create a new resolution enqueuer and feed it with the [WorldImpact]s
     // computed from kernel through the [build] in `kernel_impact.dart`.
     ResolutionEnqueuer enqueuer = new ResolutionEnqueuer(
         compiler.enqueuer,
         compiler.options,
@@ skipping 65 matching lines @@
       compiler.libraryLoader.libraries);
   enqueuer.forEach((work) {
     AstElement element = work.element;
     ResolutionImpact resolutionImpact = build(compiler, element.resolvedAst);
     WorldImpact worldImpact = compiler.backend.impactTransformer
         .transformResolutionImpact(enqueuer, resolutionImpact);
     enqueuer.applyImpact(worldImpact, impactSource: element);
   });
   return enqueuer.worldBuilder.closeWorld(compiler.reporter);
 }