Revert "Various redemptions"

pkg/compiler/lib/src/js_model/closure.dart

Index: pkg/compiler/lib/src/js_model/closure.dart
diff --git a/pkg/compiler/lib/src/js_model/closure.dart b/pkg/compiler/lib/src/js_model/closure.dart
index 16cfea58c6bd51109c12b82fbe8312d233aaf629..153853ac9dc1b0c9b68e7d498e7b48d4c095e026 100644
--- a/pkg/compiler/lib/src/js_model/closure.dart
+++ b/pkg/compiler/lib/src/js_model/closure.dart
@@ -509,12 +509,6 @@ class ClosureFieldData extends ClosureMemberData implements FieldData {
   ClosureFieldData(MemberDefinition definition) : super(definition);
 
   @override
-  DartType getFieldType(KernelToElementMap elementMap) {
-    // A closure field doesn't have a Dart type.
-    return null;
-  }
-
-  @override
   ConstantExpression getFieldConstant(
       KernelToElementMap elementMap, FieldEntity field) {
     failedAt(