Add 'part of' in dart2js code.

lib/compiler/implementation/ssa/value_range_analyzer.dart

Index: lib/compiler/implementation/ssa/value_range_analyzer.dart
diff --git a/lib/compiler/implementation/ssa/value_range_analyzer.dart b/lib/compiler/implementation/ssa/value_range_analyzer.dart
index f4a763d727e03e430946cc0d3003a5340c4494db..79970b77c775f526d5bb86bef15c1ac17f423509 100644
--- a/lib/compiler/implementation/ssa/value_range_analyzer.dart
+++ b/lib/compiler/implementation/ssa/value_range_analyzer.dart
@@ -2,6 +2,8 @@
 // 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.
 
+part of ssa;
+
 /**
  * A [Value] represents both symbolic values like the value of a
  * parameter, or the length of an array, and concrete values, like