Forget elements from resolution also.

pkg/compiler/lib/src/compiler.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.
 
 library dart2js.compiler_base;
 
 import 'dart:async' show
     EventSink,
     Future;
 
@@ skipping 1385 matching lines @@
       }
     }
     return libraryUri;
   }
 
   void diagnoseCrashInUserCode(String message, exception, stackTrace) {
     // Overridden by Compiler in apiimpl.dart.
   }
 
   void forgetElement(Element element) {
+    resolution.forgetElement(element);
     enqueuer.forgetElement(element);
     if (element is MemberElement) {
       for (Element closure in element.nestedClosures) {
         // TODO(ahe): It would be nice to reuse names of nested closures.
         closureToClassMapper.forgetElement(closure);
       }
     }
     backend.forgetElement(element);
   }
 
@@ skipping 587 matching lines @@
           compiler.backend.impactTransformer.transformResolutionImpact(
               resolutionImpact);
       return worldImpact;
     });
   }
 
   @override
   bool hasBeenResolved(Element element) {
     return _worldImpactCache.containsKey(element);
   }
+
+  @override
+  void forgetElement(Element element) {
+    _worldImpactCache.remove(element);
+  }
 }
 
 // TODO(johnniwinther): Move [ParserTask], [PatchParserTask], [DietParserTask]
 // and [ScannerTask] here.
 class _CompilerParsing implements Parsing {
   final Compiler compiler;
 
   _CompilerParsing(this.compiler);
 
   @override
@@ skipping 33 matching lines @@
     if (_otherDependencies == null) {
       _otherDependencies = new Setlet<Element>();
     }
     _otherDependencies.add(element.implementation);
   }
 
   Iterable<Element> get otherDependencies {
     return _otherDependencies != null ? _otherDependencies : const <Element>[];
   }
 }