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"""
+main() {
+  foo(x) {
+    if (x == 0) return x;

[floitsch, 2012/10/04 11:35:26]

this will be too easy to inline. Maybe change to:
int inscrutable(int x) => x == 0 ? 0 : x | inscrutable(x & (x - 1));

+    return x;
+  }
+  var x = 1;
+  if (foo(x) == 0) {
+    x = 2;
+  }
+  print(!(1 < x));
+}""";
+
+main() {
+  // Make sure we don't introduce a new variable.
+  RegExp regexp = new RegExp("1 >= x");
+  compileAndMatch(MAIN, 'main', regexp);
+}