Use entities in the TypeMask interface.

pkg/compiler/lib/src/inferrer/type_graph_inferrer.dart

Index: pkg/compiler/lib/src/inferrer/type_graph_inferrer.dart
diff --git a/pkg/compiler/lib/src/inferrer/type_graph_inferrer.dart b/pkg/compiler/lib/src/inferrer/type_graph_inferrer.dart
index 0f27c83460a42ac29f4441b775f03c9908b91d05..a61b9e9bc476ccf2dae7c319c97d465356026583 100644
--- a/pkg/compiler/lib/src/inferrer/type_graph_inferrer.dart
+++ b/pkg/compiler/lib/src/inferrer/type_graph_inferrer.dart
@@ -11,7 +11,7 @@ import '../common/names.dart' show Identifiers;
 import '../compiler.dart' show Compiler;
 import '../constants/expressions.dart' show ConstantExpression;
 import '../constants/values.dart';
-import '../elements/resolution_types.dart' show DartType;
+import '../elements/resolution_types.dart' show DartType, InterfaceType;

[Siggi Cherem (dart-lang), 2017/01/06 20:48:36]

I assume this is pending a rebase? (ResolutionInterfaceType?)

[Johnni Winther, 2017/01/09 09:05:04]

Yes.

 import '../elements/elements.dart';
 import '../js_backend/js_backend.dart' show Annotations, JavaScriptBackend;
 import '../resolution/tree_elements.dart' show TreeElementMapping;
@@ -284,10 +284,10 @@ class TypeInformationSystem extends TypeSystem<TypeInformation> {
       // TODO(ngeoffray): Narrow to bound.
       return type;
     } else {
-      assert(annotation.isInterfaceType);
+      InterfaceType interface = annotation;
       otherType = annotation.element == closedWorld.commonElements.objectClass
           ? dynamicType.type.nonNullable()
-          : new TypeMask.nonNullSubtype(annotation.element, closedWorld);
+          : new TypeMask.nonNullSubtype(interface.element, closedWorld);
     }
     if (isNullable) otherType = otherType.nullable();
     if (type.type.isExact) {