Redo "Steps towards making dart2js JS AST templates an indepentent library."

pkg/compiler/lib/src/js/js_ast.dart

Index: pkg/compiler/lib/src/js/js_ast.dart
diff --git a/tests/language/regress_21998_lib2.dart b/pkg/compiler/lib/src/js/js_ast.dart
similarity index 57%
copy from tests/language/regress_21998_lib2.dart
copy to pkg/compiler/lib/src/js/js_ast.dart
index 8d1ac8934162980fe9353119e7b035bc27e59a09..ee8289ecf2df0aa8bf0c73727d8dac478d223ff5 100644
--- a/tests/language/regress_21998_lib2.dart
+++ b/pkg/compiler/lib/src/js/js_ast.dart
@@ -2,8 +2,12 @@
 // 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 regress_21998_lib2;
+library js_ast;
 
-import 'dart:math';
+import 'precedence.dart';
+import 'characters.dart' as charCodes;
 
-lib2_max(a, b) => max(a, b);
+part 'nodes.dart';
+part 'builder.dart';
+part 'printer.dart';
+part 'template.dart';