Fix bad optimization of instance-of with uninstantiated types (issue 5216).

tests/language/instanceof4_test.dart

+// Copyright (c) 2012, 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.
+// Dart test program for testing the instanceof operation.
+// Regression test for issue 5216.
+
+class Foo<T> {
+  bool isT() => "a string" is T;
+  bool isNotT() => "a string" is! T;
+  bool isListT() => [0, 1, 2] is List<T>;
+  bool isNotListT() => [0, 1, 2] is! List<T>;
+  bool isAlsoListT() => <int>[0, 1, 2] is List<T>;
+  bool isNeitherListT() => <int>[0, 1, 2] is! List<T>;
+}
+
+testFooString() {
+  var o = new Foo<String>();
+  Expect.isTrue(o.isT());
+  Expect.isTrue(!o.isNotT());
+  Expect.isTrue(o.isListT());
+  Expect.isTrue(!o.isNotListT());
+  Expect.isTrue(!o.isAlsoListT());
+  Expect.isTrue(o.isNeitherListT());
+  for (var i = 0; i < 4000; i++) {
+    // Make sure methods are optimized.
+    o.isT();
+    o.isNotT();
+    o.isListT();
+    o.isNotListT();
+    o.isAlsoListT();
+    o.isNeitherListT();
+  }
+  Expect.isTrue(o.isT());
+  Expect.isTrue(!o.isNotT());
+  Expect.isTrue(o.isListT());
+  Expect.isTrue(!o.isNotListT());
+  Expect.isTrue(!o.isAlsoListT());
+  Expect.isTrue(o.isNeitherListT());
+}
+
+testFooInt() {
+  var o = new Foo<int>();
+  Expect.isTrue(!o.isT());
+  Expect.isTrue(o.isNotT());
+  Expect.isTrue(o.isListT());
+  Expect.isTrue(!o.isNotListT());
+  Expect.isTrue(o.isAlsoListT());
+  Expect.isTrue(!o.isNeitherListT());
+  for (var i = 0; i < 4000; i++) {
+    // Make sure methods are optimized.
+    o.isT();
+    o.isNotT();
+    o.isListT();
+    o.isNotListT();
+    o.isAlsoListT();
+    o.isNeitherListT();
+  }
+  Expect.isTrue(!o.isT());
+  Expect.isTrue(o.isNotT());
+  Expect.isTrue(o.isListT());
+  Expect.isTrue(!o.isNotListT());
+  Expect.isTrue(o.isAlsoListT());
+  Expect.isTrue(!o.isNeitherListT());
+}
+
+main() {
+  testFooString();
+  testFooInt();
+}