Cleanup 1: split parts into their own libraries, remove unused imports

pkg/compiler/lib/src/native/behavior.dart

Index: pkg/compiler/lib/src/native/behavior.dart
diff --git a/pkg/compiler/lib/src/native/behavior.dart b/pkg/compiler/lib/src/native/behavior.dart
index cd61a71db0337704f88e9ebcd90366a704cf1a2a..3921b8e8f15ed194aa74802380f9f4656778fa98 100644
--- a/pkg/compiler/lib/src/native/behavior.dart
+++ b/pkg/compiler/lib/src/native/behavior.dart
@@ -2,7 +2,28 @@
 // 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 native;
+import '../common.dart';
+import '../common/backend_api.dart' show
+    ForeignResolver;
+import '../common/resolution.dart' show
+    Parsing,
+    Resolution;
+import '../compiler.dart' show
+    Compiler;
+import '../constants/values.dart';
+import '../core_types.dart' show
+    CoreTypes;
+import '../dart_types.dart';
+import '../elements/elements.dart';
+import '../js/js.dart' as js;
+import '../js_backend/js_backend.dart';
+import '../tree/tree.dart';
+import '../universe/side_effects.dart' show
+    SideEffects;
+import '../util/util.dart';
+
+import 'enqueue.dart';
+import 'js.dart';
 
 /// This class is a temporary work-around until we get a more powerful DartType.
 class SpecialType {