Change Enqueuer to use Entity instead of Element.

pkg/compiler/lib/src/dump_info.dart

 // Copyright (c) 2013, 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 dump_info;
 
 import 'dart:convert'
     show ChunkedConversionSink, JsonEncoder, StringConversionSink;
 
 import 'package:dart2js_info/info.dart';
@@ skipping 413 matching lines @@
       _dependencies.putIfAbsent(source, () => new Set()).add(target);
     }
   }
 
   void registerImpact(Element element, WorldImpact impact) {
     if (compiler.options.dumpInfo) {
       impacts[element] = impact;
     }
   }
 
-  void unregisterImpact(Element element) {
-    impacts.remove(element);
+  void unregisterImpact(var impactSource) {
+    impacts.remove(impactSource);
   }
 
   /**
    * Returns an iterable of [Selection]s that are used by
    * [element].  Each [Selection] contains an element that is
    * used and the selector that selected the element.
    */
   Iterable<Selection> getRetaining(Element element) {
     WorldImpact impact = impacts[element];
     if (impact == null) return const <Selection>[];
@@ skipping 152 matching lines @@
 
     ChunkedConversionSink<Object> sink = encoder.startChunkedConversion(
         new StringConversionSink.fromStringSink(buffer));
     sink.add(new AllInfoJsonCodec().encode(result));
     compiler.reporter.reportInfo(NO_LOCATION_SPANNABLE, MessageKind.GENERIC, {
       'text': "View the dumped .info.json file at "
           "https://dart-lang.github.io/dump-info-visualizer"
     });
   }
 }