Reapply change to update dart2js operator equals semantics to follow

tests/compiler/dart2js/constant_folding_test.dart

-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// 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.
 // Test constant folding on numbers.
 
 #import("compiler_helper.dart");
 
 final String NUMBER_FOLDING = """
 void main() {
   var a = 4;
   var b = 3;
@@ skipping 18 matching lines @@
 }
 """;
 
 main() {
   compileAndMatch(
       NUMBER_FOLDING, 'main', const RegExp(@"print\(7\)"));
   compileAndMatch(
       NEGATIVE_NUMBER_FOLDING, 'main', const RegExp(@"print\(1\)"));
 
   String generated = compile(NULL_EQUALS_FOLDING, 'foo');
-  RegExp regexp = const RegExp(@'eqNullB\(a\)');
+  RegExp regexp = const RegExp(@'a == null');
   Expect.isTrue(regexp.hasMatch(generated));
 
   regexp = const RegExp(@'null == b');
   Expect.isTrue(regexp.hasMatch(generated));
 
   regexp = const RegExp(@'4 === c');
   Expect.isTrue(regexp.hasMatch(generated));
 
   regexp = const RegExp("'foo' === d");
   Expect.isTrue(regexp.hasMatch(generated));
 }