anchor.diff:    }
   }
   
  -/**
  - * [_FilesToLink] stores information about a set of files to be linked together.
  - * This information is grouped into a class to allow it to be reset easily when
  - * [_SummaryBaseTestStrategyTwoPhase._createLinkerInputs] is called.
  - *
  - * The generic parameter [U] is the type of information stored for each
  - * compilation unit.
  - */
  +/// [_FilesToLink] stores information about a set of files to be linked
  +/// together.  This information is grouped into a class to allow it to be reset
  +/// easily when [_SummaryBaseTestStrategyTwoPhase._createLinkerInputs] is
  +/// called.
  +///
  +/// The generic parameter [U] is the type of information stored for each
  +/// compilation unit.
   class _FilesToLink<U> {
  -  /**
  -   * Map from absolute URI to the [U] for each compilation unit passed to
  -   * [addNamedSource].
  -   */
  +  /// Map from absolute URI to the [U] for each compilation unit passed to
  +  /// [addNamedSource].
     Map<String, U> uriToUnit = <String, U>{};
   
  -  /**
  -   * Information about summaries to be included in the link process.
  -   */
  +  /// Information about summaries to be included in the link process.
     SummaryDataStore summaryDataStore = new SummaryDataStore([]);
   }
   
  -/**
  - * Instances of the class [_LinkerInputs] encapsulate the necessary information
  - * to pass to the summary linker.
  - */
  +/// Instances of the class [_LinkerInputs] encapsulate the necessary information
  +/// to pass to the summary linker.
   class _LinkerInputs {
     final bool _allowMissingFiles;
     final Map<String, UnlinkedUnit> _uriToUnit;
  
positive.code: /// The tests themselves can then be provided via mixin, allowing summaries to
  /// be tested in a variety of ways.
  abstract class SummaryBaseTestStrategy {
    /**
     * Add the given source file so that it may be referenced by the file under
     * test.
     */
    void addNamedSource(String filePath, String contents);
  }
  
  
negative.code:   return unit;
  }
  
  /// Verify invariants of the given [linkedLibrary].
  void _validateLinkedLibrary(LinkedLibrary linkedLibrary) {
    for (LinkedUnit unit in linkedLibrary.units) {
      for (LinkedReference reference in unit.references) {
  