dart2js: Rename old emitter to full emitter and make it its own library.

pkg/compiler/lib/src/js_emitter/native_emitter.dart

 // Copyright (c) 2012, 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 dart2js.js_emitter;
 
 class NativeEmitter {
 
-  final Map<Element, ClassBuilder> cachedBuilders;
+  // TODO(floitsch): the native-emitter should not know about ClassBuilders.
+  final Map<Element, full_js_emitter.ClassBuilder> cachedBuilders;
 
   final CodeEmitterTask emitterTask;
 
   // Whether the application contains native classes.
   bool hasNativeClasses = false;
 
   // Caches the native subtypes of a native class.
   Map<ClassElement, List<ClassElement>> subtypes;
 
   // Caches the direct native subtypes of a native class.
@@ skipping 322 matching lines @@
     // used.  We should also use an interceptor if the check can't be satisfied
     // by a native class in case we get a native instance that tries to spoof
     // the type info.  i.e the criteria for whether or not to use an interceptor
     // is whether the receiver can be native, not the type of the test.
     if (element == null || !element.isClass) return false;
     ClassElement cls = element;
     if (Elements.isNativeOrExtendsNative(cls)) return true;
     return isSupertypeOfNativeClass(element);
   }
 }