dart2js cleanup: remove unused imports and variables

pkg/compiler/lib/src/ssa/value_range_analyzer.dart

Index: pkg/compiler/lib/src/ssa/value_range_analyzer.dart
diff --git a/pkg/compiler/lib/src/ssa/value_range_analyzer.dart b/pkg/compiler/lib/src/ssa/value_range_analyzer.dart
index 8893e90ee75904a51de9529987fafae17c0652c9..c811c714fa00e208e9b5ce59311e06acf62d2d1d 100644
--- a/pkg/compiler/lib/src/ssa/value_range_analyzer.dart
+++ b/pkg/compiler/lib/src/ssa/value_range_analyzer.dart
@@ -2,13 +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.
 
-import '../common/codegen.dart' show CodegenRegistry, CodegenWorkItem;
+import '../common/codegen.dart' show CodegenWorkItem;
 import '../compiler.dart' show Compiler;
 import '../constant_system_dart.dart';
 import '../constants/constant_system.dart';
 import '../constants/values.dart';
 import '../js_backend/js_backend.dart';
-
 import 'nodes.dart';
 import 'optimize.dart';