anchor.diff:  import 'package:analyzer/src/generated/incremental_resolution_validator.dart';
   import 'package:analyzer/src/services/lint.dart';
   import 'package:analyzer/src/task/task_dart.dart';
  -import 'package:analyzer/src/util/lru_map.dart';
   
   import '../../instrumentation/instrumentation.dart';
   import 'ast.dart';
  
positive.code:    * A cache of content used to override the default content of a source.
     */
    ContentCache _contentCache = new ContentCache();
  
    /**
     * A cache of content used to override the default content of a source
     * before the corresponding override was removed from [_contentCache].
     */
    LRUMap<Source, String> _prevOverlayCache = new LRUMap<Source, String>(5);
  
    /**
     * The source factory used to create the sources that can be analyzed in this context.
  
negative.code:         TimestampedData<String> fileContents = getContents(source);
          String fileContentsData = fileContents.data;
          if (fileContentsData == originalContents) {
            sourceEntry.setValue(SourceEntry.CONTENT, fileContentsData);
            sourceEntry.modificationTime = fileContents.modificationTime;
            changed = false;
          }
  