Add some tests for calls with checks in strong mode.

tests/language_strong/covariant_subtyping_tearoff3_test.dart

+// Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
+// 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.
+import 'package:expect/expect.dart';
+
+class Implementation {
+  dynamic method(int x) {}
+}
+
+abstract class Interface1<T> {
+  dynamic method(T x);
+}
+
+abstract class Interface2<T> {
+  dynamic method(T x);
+}
+
+class Subclass extends Implementation
+    implements Interface1<int>, Interface2<int> {}
+
+typedef dynamic TakeNum(num x);
+
+main() {
+  Subclass subclass = new Subclass();
+
+  Interface1<int> intInterface1 = subclass;
+  Interface1<num> numInterface1 = intInterface1;
+  TakeNum f1 = numInterface1.method;
+  Expect.throws(() => f1(2.5));
+  dynamic f1dynamic = f1;
+  Expect.throws(() => f1dynamic(2.5));
+
+  Interface2<int> intInterface2 = subclass;
+  Interface2<num> numInterface2 = intInterface2;
+  TakeNum f2 = numInterface2.method;
+  Expect.throws(() => f2(2.5));
+  dynamic f2dynamic = f2;
+  Expect.throws(() => f2dynamic(2.5));
+}