Don't constant fold operation if result is incompatible with it.

tests/language/vm/regress_22480_test.dart

 // Copyright (c) 2014, 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.
 // VMOptions=--optimization_counter_threshold=10
 
 import 'package:expect/expect.dart';
 
-trunc(x) => x & 0xFFFFFFFF;
-
-foo(t, x) => t(x >> 15);
+test(j) {
+  var result = true;
+  j++;
+  for (var i = 0; i < 100; i++) {
+    result = (i < 50 || j < (1 << 32)) && result;
+  }
+  return result;
+}
 
 main() {
-  for (var i = 0; i < 20000; i++) {
-    Expect.equals(0x00010000, foo(trunc, 0x80000000));
-  }
-  for (var i = 0; i < 20000; i++) {
-    Expect.equals(0x10000000, foo(trunc, 0x80000000000));
-  }
+  Expect.isTrue(test(30));
 }