dart2js: fix typo in incremental compilation fix.

pkg/dart2js_incremental/lib/library_updater.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.
 
 library dart2js_incremental.library_updater;
 
 import 'dart:async' show
     Future;
 
 import 'dart:convert' show
@@ skipping 1240 matching lines @@
     return element;
   }
 
   void writeUpdateJsOn(List<jsAst.Statement> updates) {
     if (!wasStateCaptured) {
       throw new StateError(
           "captureState must be called before writeUpdateJsOn.");
     }
 
     updates.add(
-        js.statement('delete #.prototype.#', [prototypeAccess, getterName]));
+        js.statement('delete #.#', [prototypeAccess, getterName]));
     updates.add(
-        js.statement('delete #.prototype.#', [prototypeAccess, setterName]));
+        js.statement('delete #.#', [prototypeAccess, setterName]));
   }
 }
 
 class AddedFunctionUpdate extends Update with JsFeatures {
   final PartialFunctionElement element;
 
   final /* ScopeContainerElement */ container;
 
   AddedFunctionUpdate(Compiler compiler, this.element, this.container)
       : super(compiler) {
@@ skipping 200 matching lines @@
   List<String> computeFields(ClassElement cls) {
     // TODO(ahe): Rewrite for new emitter.
     ClassBuilder builder = new ClassBuilder(cls, namer);
     classEmitter.emitFields(cls, builder);
     return builder.fields;
   }
 }
 
 // TODO(ahe): Remove this method.
 NO_WARN(x) => x;