Fix host checked mode failure.

tests/compiler/dart2js/gvn_test.dart

 // Copyright (c) 2011, 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 'compiler_helper.dart';
 
 const String TEST_ONE = r"""
 void foo(bar) {
   for (int i = 0; i < 1; i++) {
     print(1 + bar);
     print(1 + bar);
   }
 }
 """;
 
 // Check that modulo does not have any side effect and we are
 // GVN'ing the length of [:list:].
 const String TEST_TWO = r"""
 void foo(a) {
   var list = new List<int>();
   list[0] = list[0 % a];
   list[1] = list[1 % a];
 }
 """;
 
+// Check that is checks get GVN'ed.
+const String TEST_THREE = r"""
+void foo(a) {
+  print(a is num);
+  print(a is num);
+}
+""";
+
+// Check that instructions that don't have a builtin equivalent can
+// still be GVN'ed.
+const String TEST_FOUR = r"""
+void foo(a) {
+  print(1 >> a);
+  print(1 >> a);
+}
+""";
+
 main() {
   String generated = compile(TEST_ONE, entry: 'foo');
   RegExp regexp = new RegExp(r"1 \+ [a-z]+");
   checkNumberOfMatches(regexp.allMatches(generated).iterator, 1);
 
   generated = compile(TEST_TWO, entry: 'foo');
   checkNumberOfMatches(new RegExp("length").allMatches(generated).iterator, 1);
+
+  generated = compile(TEST_THREE, entry: 'foo');
+  checkNumberOfMatches(new RegExp("number").allMatches(generated).iterator, 1);
+
+  generated = compile(TEST_FOUR, entry: 'foo');
+  checkNumberOfMatches(new RegExp("shr").allMatches(generated).iterator, 1);
 }