Split implementation of KernelToElementMapImpl

pkg/compiler/lib/src/js_emitter/runtime_type_generator.dart

Index: pkg/compiler/lib/src/js_emitter/runtime_type_generator.dart
diff --git a/pkg/compiler/lib/src/js_emitter/runtime_type_generator.dart b/pkg/compiler/lib/src/js_emitter/runtime_type_generator.dart
index f6f398f77c6df56cc718b95b710d3d55fc514fa6..c9cb83ec2481c8fad2c8b71623ebf82f6ce8543c 100644
--- a/pkg/compiler/lib/src/js_emitter/runtime_type_generator.dart
+++ b/pkg/compiler/lib/src/js_emitter/runtime_type_generator.dart
@@ -345,7 +345,7 @@ class RuntimeTypeGenerator {
         // A superclass might already implement the Function interface. In such
         // a case, we can avoid emitting the is test here.
         ClassEntity superclass = _elementEnvironment.getSuperClass(cls);
-        if (!_closedWorld.isSubclassOf(
+        if (!_closedWorld.isSubtypeOf(
             superclass, _commonElements.functionClass)) {
           _generateInterfacesIsTests(_commonElements.functionClass,
               generateIsTest, generateSubstitution, generated);