anchor.diff:  import 'package:analyzer/src/generated/parser.dart';
   import 'package:analyzer/src/generated/source.dart';
   import 'package:analyzer/src/generated/source_io.dart';
  +import 'package:analyzer/src/summary/format.dart';
  +import 'package:analyzer/src/summary/summarize_ast.dart';
   import 'package:kernel/analyzer/loader.dart';
   import 'package:kernel/kernel.dart';
   import 'package:package_config/discovery.dart';
  
positive.code:   report("parse", pTime);
  }
  
  /// Add to [files] all sources reachable from [start].
  void collectSources(Source start, Set<Source> files) {
    if (!files.add(start)) return;
  
negative.code:   var token = tokenize(source);
    var parser = new Parser(source, AnalysisErrorListener.NULL_LISTENER);
    return parser.parseCompilationUnit(token);
  }
  
  UnlinkedUnitBuilder unlinkedSummarize(Source source) {
    var unit = parseFull(source);
    return serializeAstUnlinked(unit);
  }
  
  /// Scan [source] and return the first token produced by the scanner.
  