Revert "Only emit typeguards if we think they are valuable."

frog/tests/leg/src/CodeMotionTest.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");
 
 final String TEST_ONE = @"""
 foo(int param0, int param1, bool param2) {
-  for (int i = 0; i < 1; i++) {
-    var x = param0 + 5;  // '+' is now GVNed.
-    if (param2) {
-      print(param0 + param1);
-    } else {
-      print(param0 + param1);
-    }
+  var x = param0 + 5;  // '+' is now GVNed.
+  if (param2) {
+    print(param0 + param1);
+  } else {
+    print(param0 + param1);
   }
 }
 """;
 
 main() {
   String generated = compile(TEST_ONE, 'foo');
   RegExp regexp = const RegExp('param0 \\+ param1');
   Iterator matches = regexp.allMatches(generated).iterator();
   Expect.isTrue(matches.hasNext());
   matches.next();
   Expect.isFalse(matches.hasNext());
 }