Use the correct inputs when checking if inverse operator can be used.

tests/compiler/dart2js/inverse_operator_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.
 
+#import("compiler_helper.dart");
+
+const String MAIN = r"""
 int inscrutable(int x) => x == 0 ? 0 : x | inscrutable(x & (x - 1));
+main() {
+  var x = 1;
+  if (inscrutable(x) == 0) {
+    x = 2;
+  }
+  print(!(1 < x));
+}""";
 
 main() {
-  var things = [0, double.INFINITY, double.NEGATIVE_INFINITY];
-  var first = things[1];
-  var second = things[2];
-  Expect.isFalse(first is int);
-  Expect.isFalse(second is int);
-  Expect.isTrue(first is double);
-  Expect.isTrue(second is double);
+  // Make sure we don't introduce a new variable.
+  RegExp regexp = new RegExp("1 >= x");
+  compileAndMatch(MAIN, 'main', regexp);
 }