Test closed world model after deserialization.

pkg/compiler/lib/src/elements/modelx.dart

Index: pkg/compiler/lib/src/elements/modelx.dart
diff --git a/pkg/compiler/lib/src/elements/modelx.dart b/pkg/compiler/lib/src/elements/modelx.dart
index be8b45cf97ea4daa55f0b247b3ecdecf4e6bb200..bed7ceab5d75bb77881adc235fdb1b0ee357414c 100644
--- a/pkg/compiler/lib/src/elements/modelx.dart
+++ b/pkg/compiler/lib/src/elements/modelx.dart
@@ -13,8 +13,6 @@ import '../compiler.dart' show
 import '../constants/constant_constructors.dart';
 import '../constants/constructors.dart';
 import '../constants/expressions.dart';
-import '../core_types.dart' show
-    CoreClasses;
 import '../dart_types.dart';
 import '../diagnostics/messages.dart' show
     MessageTemplate;
@@ -2701,11 +2699,6 @@ abstract class BaseClassElementX extends ElementX
     backendMembers.forEach(f);
   }
 
-  bool implementsFunction(CoreClasses coreClasses) {
-    return asInstanceOf(coreClasses.functionClass) != null ||
-        callType != null;
-  }
-
   // TODO(johnniwinther): Remove these when issue 18630 is fixed.
   ClassElement get patch => super.patch;
   ClassElement get origin => super.origin;