Remove requiredTypes

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

Index: pkg/compiler/lib/src/resolution/resolution.dart
diff --git a/pkg/compiler/lib/src/resolution/resolution.dart b/pkg/compiler/lib/src/resolution/resolution.dart
index 2b65e42e00f48965b702a86d27a98400b5601e59..a65fce4e49bfbda3eb4516787154b21c6264f9b8 100644
--- a/pkg/compiler/lib/src/resolution/resolution.dart
+++ b/pkg/compiler/lib/src/resolution/resolution.dart
@@ -22,6 +22,8 @@ import '../compile_time_constants.dart' show
     ConstantCompiler;
 import '../constants/values.dart' show
     ConstantValue;
+import '../core_types.dart' show
+    CoreTypes;
 import '../dart_types.dart';
 import '../elements/elements.dart';
 import '../elements/modelx.dart' show
@@ -70,6 +72,8 @@ class ResolverTask extends CompilerTask {
 
   Parsing get parsing => compiler.parsing;
 
+  CoreTypes get coreTypes => compiler.coreTypes;
+
   ResolutionImpact resolve(Element element) {
     return measure(() {
       if (Elements.isErroneous(element)) {
@@ -364,7 +368,7 @@ class ResolverTask extends CompilerTask {
       reporter.reportErrorMessage(
           element, MessageKind.FINAL_WITHOUT_INITIALIZER);
     } else {
-      registry.registerInstantiatedClass(compiler.nullClass);
+      registry.registerInstantiatedType(coreTypes.nullType);
     }
 
     if (Elements.isStaticOrTopLevelField(element)) {