Consistently use implements when one interface inherits from another interface

pkg/analyzer/lib/task/model.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library analyzer.task.model;
 
 import 'dart:collection';
 import 'dart:developer';
 
 import 'package:analyzer/src/generated/engine.dart' hide AnalysisTask;
@@ skipping 332 matching lines @@
   @override
   ListTaskInput<E> of(AnalysisTarget target, {bool flushOnAccess: false});
 }
 
 /**
  * A description of an input to an [AnalysisTask] that can be used to compute
  * that input.
  *
  * Clients may not extend, implement or mix-in this class.
  */
-abstract class ListTaskInput<E> extends TaskInput<List<E>> {
+abstract class ListTaskInput<E> implements TaskInput<List<E>> {
   /**
    * Return a task input that can be used to compute a flatten list whose
    * elements are combined [subListResult]'s associated with those elements.
    */
   ListTaskInput /*<V>*/ toFlattenListOf(
       ListResultDescriptor /*<V>*/ subListResult);
 
   /**
    * Return a task input that can be used to compute a list whose elements are
    * the result of passing the elements of this input to the [mapper] function.
@@ skipping 21 matching lines @@
    */
   MapTaskInput<AnalysisTarget, dynamic /*V*/ > toMapOf(
       ResultDescriptor /*<V>*/ valueResult);
 }
 
 /**
  * A description of an input with a [Map] based values.
  *
  * Clients may not extend, implement or mix-in this class.
  */
-abstract class MapTaskInput<K, V> extends TaskInput<Map<K, V>> {
+abstract class MapTaskInput<K, V> implements TaskInput<Map<K, V>> {
   /**
    * [V] must be a [List].
    * Return a task input that can be used to compute a list whose elements are
    * the result of passing keys [K] and the corresponding elements of [V] to
    * the [mapper] function.
    */
   TaskInput<List /*<E>*/ > toFlattenList(
       BinaryFunction<K, dynamic /*element of V*/, dynamic /*<E>*/ > mapper);
 }
 
@@ skipping 329 matching lines @@
   /**
    * A work should be done, but without any special urgency.
    */
   NORMAL,
 
   /**
    * Nothing to do.
    */
   NONE
 }