Extract ClosedWorldRefiner implementation from ClosedWorldImpl to ClosedWorldBase

pkg/compiler/lib/src/enqueue.dart

Index: pkg/compiler/lib/src/enqueue.dart
diff --git a/pkg/compiler/lib/src/enqueue.dart b/pkg/compiler/lib/src/enqueue.dart
index 8f37fe92110ec247c46728d27aa5195281bb66ba..e9a44818ab66452597081b5df7d72a5dbb08b945 100644
--- a/pkg/compiler/lib/src/enqueue.dart
+++ b/pkg/compiler/lib/src/enqueue.dart
@@ -91,7 +91,7 @@ abstract class Enqueuer {
   void checkQueueIsEmpty();
   void logSummary(void log(String message));
 
-  Iterable<Entity> get processedEntities;
+  Iterable<MemberEntity> get processedEntities;
 
   Iterable<ClassEntity> get processedClasses;
 }
@@ -205,7 +205,7 @@ class ResolutionEnqueuer extends EnqueuerImpl {
   WorldImpactVisitor _impactVisitor;
 
   /// All declaration elements that have been processed by the resolver.
-  final Set<Entity> _processedEntities = new Set<Entity>();
+  final Set<MemberEntity> _processedEntities = new Set<MemberEntity>();
 
   final Queue<WorkItem> _queue = new Queue<WorkItem>();
 
@@ -405,7 +405,7 @@ class ResolutionEnqueuer extends EnqueuerImpl {
 
   String toString() => 'Enqueuer($name)';
 
-  Iterable<Entity> get processedEntities => _processedEntities;
+  Iterable<MemberEntity> get processedEntities => _processedEntities;
 
   ImpactUseCase get impactUse => IMPACT_USE;
 
@@ -421,7 +421,7 @@ class ResolutionEnqueuer extends EnqueuerImpl {
 
   /// Registers [entity] as processed by the resolution enqueuer. Used only for
   /// testing.
-  void registerProcessedElementInternal(Entity entity) {
+  void registerProcessedElementInternal(MemberEntity entity) {
     _processedEntities.add(entity);
   }