Reapply "Refactor constant part." (r4958) with fixes.

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;
@@ skipping 30 matching lines @@
 main(a) {
   print(a[0]);
   while (true) {
     a[0] = a[1];
   }
 }
 """;
 
 main() {
   String generated = compile(TEST_ONE, 'sum');
-  RegExp regexp = new RegExp("i = \\(?$anyIdentifier \\+ 1\\)?");
+  RegExp regexp = new RegExp("i = \\(?$anyIdentifier \\+ \\(1\\)\\)?");
   Expect.isTrue(regexp.hasMatch(generated));
 
   regexp = new RegExp("sum = \\(?$anyIdentifier \\+ $anyIdentifier\\)?");
   Expect.isTrue(regexp.hasMatch(generated));
 
   regexp = const RegExp("typeof param0 !== 'number'");
   Expect.isTrue(regexp.hasMatch(generated));
 
   regexp = const RegExp("typeof param1 !== 'number'");
   Expect.isTrue(regexp.hasMatch(generated));
@@ skipping 18 matching lines @@
   Expect.isTrue(regexp.hasMatch(generated));
   Expect.isTrue(!generated.contains('index'));
   Expect.isTrue(!generated.contains('indexSet'));
 
   generated = compile(TEST_FIVE, 'foo');
   regexp = const RegExp('a.constructor !== Array');
   Expect.isTrue(regexp.hasMatch(generated));
   Expect.isTrue(!generated.contains('index'));
   Expect.isTrue(!generated.contains('indexSet'));
 }