Move towards using WorldImpact for codegen

pkg/compiler/lib/src/native/enqueue.dart

Index: pkg/compiler/lib/src/native/enqueue.dart
diff --git a/pkg/compiler/lib/src/native/enqueue.dart b/pkg/compiler/lib/src/native/enqueue.dart
index 166e6cf8295b4fccea36fb214ef43f09e2f4741d..1ab06feb9c789a4834715a5f98a605230b813b59 100644
--- a/pkg/compiler/lib/src/native/enqueue.dart
+++ b/pkg/compiler/lib/src/native/enqueue.dart
@@ -47,7 +47,7 @@ class NativeEnqueuer {
   void handleMethodAnnotations(Element method) {}
 
   /// Returns whether native classes are being used.
-  bool hasInstantiatedNativeClasses() => false;
+  bool get hasInstantiatedNativeClasses => false;
 
   /// Emits a summary information using the [log] function.
   void logSummary(log(message)) {}
@@ -73,7 +73,7 @@ abstract class NativeEnqueuerBase implements NativeEnqueuer {
 
   final Set<LibraryElement> processedLibraries;
 
-  bool hasInstantiatedNativeClasses() => !registeredClasses.isEmpty;
+  bool get hasInstantiatedNativeClasses => !registeredClasses.isEmpty;
 
   final Set<ClassElement> nativeClassesAndSubclasses = new Set<ClassElement>();