anchor.diff:          TimestampedData<String> fileContents = getContents(source);
           String fileContentsData = fileContents.data;
           if (fileContentsData == originalContents) {
  -          _prevOverlayCache.put(source, fileContentsData);
  +          sourceEntry.setValue(SourceEntry.CONTENT, fileContentsData);
             sourceEntry.modificationTime = fileContents.modificationTime;
             changed = false;
           }
  
positive.code: 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';
  
negative.code:       return;
      }
      // Check if the content of the source is the same as it was the last time.
      String sourceContent = sourceEntry.getValue(SourceEntry.CONTENT);
      if (sourceContent != null) {
        sourceEntry.setState(SourceEntry.CONTENT, CacheState.FLUSHED);
        try {
          TimestampedData<String> fileContents = getContents(source);
          if (fileContents.data == sourceContent) {
  