A type should be a subtype of Function if its class declares a call function,

tests/language/regress_25550_test.dart

Index: tests/language/regress_25550_test.dart
diff --git a/tests/standalone/no_support_ast_printer_test.dart b/tests/language/regress_25550_test.dart
similarity index 57%
copy from tests/standalone/no_support_ast_printer_test.dart
copy to tests/language/regress_25550_test.dart
index bbffe2254938bb44f1310aafbd039d05d840c1d8..4a8a7c5954d202d9a9d53f401efb13be36277c0b 100644
--- a/tests/standalone/no_support_ast_printer_test.dart
+++ b/tests/language/regress_25550_test.dart
@@ -2,8 +2,16 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// VMOptions=--no-support_ast_printer
+typedef int Adder(int a, int b);
+
+class Mock {
+  noSuchMethod(i) => null;
+}
+
+class MockAdder extends Mock {
+  int call(int a, int b);
+}
 
 main() {
-  print("Okay");
+  Adder adder = new MockAdder();
 }