Gather and report stats on the number of times flushed results are recomputed

pkg/analyzer/lib/task/model.dart

Index: pkg/analyzer/lib/task/model.dart
diff --git a/pkg/analyzer/lib/task/model.dart b/pkg/analyzer/lib/task/model.dart
index 557a763d7a4993226327fefd71a2b54d322eb0ab..dd1062fc9f067fe46da68cdb94428656c1d56b27 100644
--- a/pkg/analyzer/lib/task/model.dart
+++ b/pkg/analyzer/lib/task/model.dart
@@ -457,6 +457,13 @@ abstract class ResultCachingPolicy<T> {
  */
 abstract class ResultDescriptor<V> {
   /**
+   * A comparator that can be used to sort result descriptors by their name.
+   */
+  static final Comparator<ResultDescriptor> SORT_BY_NAME =
+      (ResultDescriptor first, ResultDescriptor second) =>
+          first.name.compareTo(second.name);
+
+  /**
    * Initialize a newly created analysis result to have the given [name] and
    * [defaultValue].
    *