Remove code supporting incremental compilation in dart2js

pkg/compiler/lib/src/js_emitter/lazy_emitter/emitter.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.js_emitter.lazy_emitter;
 
 import 'package:js_runtime/shared/embedded_names.dart' show JsBuiltin;
 
 import '../../common.dart';
 import '../../compiler.dart' show Compiler;
@@ skipping 174 matching lines @@
       default:
         reporter.internalError(
             NO_LOCATION_SPANNABLE, "Unhandled Builtin: $builtin");
         return null;
     }
   }
 
   @override
   // TODO(het): Generate this correctly
   int generatedSize(OutputUnit unit) => 0;
-
-  @override
-  void invalidateCaches() {}
 }