Do not generate at use site loop phis. It requires live analysis that we currently don't implement.

frog/tests/leg/src/TypeInferenceTest.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 = @"""
 sum(param0, param1) {
   var sum = 0;
   for (var i = param0; i < param1; i += 1) sum = sum + i;
   return sum;
 }
 """;
 
+String anyIdentifier = "[a-zA-Z][a-zA-Z0-9]*";
+
 main() {
   String generated = compile(TEST_ONE, 'sum');
-  RegExp regexp = const RegExp("i = \\(i \\+ 1\\)");
+  RegExp regexp = new RegExp("i = \\($anyIdentifier \\+ 1\\)");
   Expect.isTrue(regexp.hasMatch(generated));
 
-  regexp = const RegExp("sum = \\(sum \\+ i\\)");
+  regexp = new RegExp("sum = \\($anyIdentifier \\+ $anyIdentifier\\)");
   Expect.isTrue(regexp.hasMatch(generated));
 
   regexp = const RegExp('guard\\\$num\\(param0\\)');
   Expect.isTrue(regexp.hasMatch(generated));
 
   regexp = const RegExp('guard\\\$num\\(param1\\)');
   Expect.isTrue(regexp.hasMatch(generated));
 }