more progress implementing analysis server code completion

pkg/analysis_server/lib/src/collections.dart

Index: pkg/analysis_server/lib/src/collections.dart
diff --git a/pkg/analysis_server/lib/src/collections.dart b/pkg/analysis_server/lib/src/collections.dart
index 1c5fefc17d7ce90dc79a66af4858d676e7a584c7..f85bc975cffdbe72a7cf396956b40879ec5cedc6 100644
--- a/pkg/analysis_server/lib/src/collections.dart
+++ b/pkg/analysis_server/lib/src/collections.dart
@@ -16,15 +16,3 @@ Iterable concat(Iterable<Iterable> iterables) => iterables.expand((x) => x);
  * Returns the concatentation of the input iterables as a [List].
  */
 List concatToList(Iterable<Iterable> iterables) => concat(iterables).toList();
-
-
-/**
- * Instances of the class [HasToJson] implement [toJson] method that returns
- * a JSON presentation.
- */
-abstract class HasToJson {
-  /**
-   * Returns a JSON presentation of the object.
-   */
-  Map<String, Object> toJson();
-}