Fix host checked mode failure.

tests/compiler/dart2js/gvn_test.dart

Index: tests/compiler/dart2js/gvn_test.dart
===================================================================
--- tests/compiler/dart2js/gvn_test.dart	(revision 17449)
+++ tests/compiler/dart2js/gvn_test.dart	(working copy)
@@ -23,6 +23,23 @@
 }
 """;
 
+// 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]+");
@@ -30,4 +47,10 @@
 
   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);
 }