Reset compilation unit in notification, as it might be damaged.

pkg/analyzer/lib/src/generated/engine.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.
 
 // This code was auto-generated, is not intended to be edited, and is subject to
 // significant change. Please see the README file for more information.
 
 library engine;
 
 import "dart:math" as math;
@@ skipping 5004 matching lines @@
     PoorMansIncrementalResolver resolver = new PoorMansIncrementalResolver(
         typeProvider,
         unitSource,
         dartEntry,
         analysisOptions.incrementalApi);
     bool success = resolver.resolve(oldUnit, newCode);
     AnalysisEngine.instance.instrumentationService.logPerformance(
         AnalysisPerformanceKind.INCREMENTAL,
         perfCounter,
         'success=$success,context_id=$_id,code_length=${newCode.length}');
+    // if failed, reset compilation unit in notification, it is damaged now
     if (!success) {
+      ChangeNoticeImpl notice = _getNotice(unitSource);
+      notice.compilationUnit = null;

[Brian Wilkerson, 2015/01/12 22:37:02]

Is the compilation unit in the cache marked as invalid? If not, I think this can
produce a loss of information.

       return false;
     }
     // if validation, remember the result, but throw it away
     if (analysisOptions.incrementalValidation) {
       incrementalResolutionValidation_lastUnitSource = oldUnit.element.source;
       incrementalResolutionValidation_lastLibrarySource =
           oldUnit.element.library.source;
       incrementalResolutionValidation_lastUnit = oldUnit;
       return false;
     }
@@ skipping 7160 matching lines @@
     if (element.id == _id) {
       result = element;
       throw new _ElementByIdFinderException();
     }
     super.visitElement(element);
   }
 }
 
 class _ElementByIdFinderException {
 }