Redo "Use an explicit 'this' parameter instead of 'This' nodes."

tests/compiler/dart2js/backend_dart/sexpr_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.
 
 library dart_backend.sexpr_test;
 
 import 'dart:async';
 
 import 'package:async_helper/async_helper.dart';
 import 'package:compiler/src/dart2jslib.dart';
@@ skipping 142 matching lines @@
           , "TypeOperator"
 
           // Primitives
           , "Constant"
           , "CreateFunction"
           , "GetMutableVariable"
           , "LiteralList"
           , "LiteralMap"
           // Parameters are encoded by name only and hence are not in this list.
           , "ReifyTypeVar"
-          , "This"
+
+          , "(this)"   // 'this' Parameter declarations
+          , "this"     // 'this' Parameter uses
+
           ];
 
   asyncTest(() => testStringifier(CODE, tokens).then((List<String> sexprs) {
     final functions = testUnstringifier(sexprs);
 
     // Ensure that
     // stringified(CODE) == stringified(unstringified(stringified(CODE)))
     Expect.listEquals(sexprs, stringifyAll(functions));
   }));
 }