Revert "Move towards using WorldImpact for codegen"

pkg/compiler/lib/src/resolution/registry.dart

Index: pkg/compiler/lib/src/resolution/registry.dart
diff --git a/pkg/compiler/lib/src/resolution/registry.dart b/pkg/compiler/lib/src/resolution/registry.dart
index da2c129a097142e08c1c09fadca8985a9859293e..d6aa72c37cd16a67b26de9d680aa2561da34ebc3 100644
--- a/pkg/compiler/lib/src/resolution/registry.dart
+++ b/pkg/compiler/lib/src/resolution/registry.dart
@@ -18,15 +18,16 @@ import '../universe/call_structure.dart' show CallStructure;
 import '../universe/feature.dart';
 import '../universe/selector.dart' show Selector;
 import '../universe/use.dart' show DynamicUse, StaticUse, TypeUse;
-import '../universe/world_impact.dart' show WorldImpact, WorldImpactBuilderImpl;
+import '../universe/world_impact.dart' show WorldImpact, WorldImpactBuilder;
 import '../util/enumset.dart' show EnumSet;
 import '../util/util.dart' show Setlet;
 import 'members.dart' show ResolverVisitor;
 import 'send_structure.dart';
 import 'tree_elements.dart' show TreeElementMapping;
 
-class ResolutionWorldImpactBuilder extends WorldImpactBuilderImpl
-    implements NativeRegistry, ResolutionImpact {
+class ResolutionWorldImpactBuilder extends ResolutionImpact
+    with WorldImpactBuilder
+    implements NativeRegistry {
   final String name;
   EnumSet<Feature> _features;
   Setlet<MapLiteralUse> _mapLiterals;