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

pkg/compiler/lib/src/native/behavior.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.
 
-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 {
   final String name;
   const SpecialType._(this.name);
 
   /// The type Object, but no subtypes:
   static const JsObject = const SpecialType._('=Object');
 
   int get hashCode => name.hashCode;
@@ skipping 874 matching lines @@
         MessageKind.GENERIC,
         {'text': "Type '$typeString' not found."});
     return const DynamicType();
   }
 
   static _errorNode(locationNodeOrElement, Parsing parsing) {
     if (locationNodeOrElement is Node) return locationNodeOrElement;
     return locationNodeOrElement.parseNode(parsing);
   }
 }