Create ResolutionEnqueuer after library loading.

tests/compiler/dart2js/memory_compiler.dart

Index: tests/compiler/dart2js/memory_compiler.dart
diff --git a/tests/compiler/dart2js/memory_compiler.dart b/tests/compiler/dart2js/memory_compiler.dart
index 89661daaa5de45296e3ed67b5cbd4514459b22fa..9137c9085b9566928876aea818f9830c6999d4c2 100644
--- a/tests/compiler/dart2js/memory_compiler.dart
+++ b/tests/compiler/dart2js/memory_compiler.dart
@@ -15,6 +15,7 @@ import 'package:compiler/compiler_new.dart'
         Diagnostic,
         PackagesDiscoveryProvider;
 import 'package:compiler/src/diagnostics/messages.dart' show Message;
+import 'package:compiler/src/enqueue.dart' show ResolutionEnqueuer;
 import 'package:compiler/src/null_compiler_output.dart' show NullCompilerOutput;
 import 'package:compiler/src/library_loader.dart' show LoadedLibraries;
 import 'package:compiler/src/options.dart' show CompilerOptions;
@@ -178,6 +179,7 @@ CompilerImpl compilerFor(
     // TODO(johnniwinther): Assert that no libraries are loaded lazily from
     // this call.
     compiler.onLibrariesLoaded(new MemoryLoadedLibraries(copiedLibraries));
+    ResolutionEnqueuer resolutionEnqueuer = compiler.startResolution();
 
     compiler.backend.constantCompilerTask
         .copyConstantValues(cachedCompiler.backend.constantCompilerTask);
@@ -186,7 +188,7 @@ CompilerImpl compilerFor(
         cachedCompiler.enqueuer.resolution.processedEntities;
     cachedTreeElements.forEach((element) {
       if (element.library.isPlatformLibrary) {
-        compiler.enqueuer.resolution.registerProcessedElementInternal(element);
+        resolutionEnqueuer.registerProcessedElementInternal(element);
       }
     });