Fix hints and clean-up obsolete comment syntax (TBR)

pkg/analysis_server/lib/src/collections.dart

 // Copyright (c) 2014, 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.
 
 /**
  * Returns the concatenation of the input [iterables].
  *
  * The returned iterable is a lazily-evaluated view on the input iterables.
  */
-Iterable/*<E>*/ concat/*<E>*/(Iterable<Iterable/*<E>*/ > iterables) =>
+Iterable<E> concat<E>(Iterable<Iterable<E>> iterables) =>
     iterables.expand((x) => x);
 
 /**
  * Returns the concatenation of the input [iterables] as a [List].
  */
-List/*<E>*/ concatToList/*<E>*/(Iterable<Iterable/*<E>*/ > iterables) =>
+List<E> concatToList<E>(Iterable<Iterable<E>> iterables) =>
     concat(iterables).toList();
 
 /**
  * Returns the given [list] if it is not empty, or `null` otherwise.
  */
-List/*<E>*/ nullIfEmpty/*<E>*/(List/*<E>*/ list) {
+List<E> nullIfEmpty<E>(List<E> list) {
   if (list == null) {
     return null;
   }
   if (list.isEmpty) {
     return null;
   }
   return list;
 }
 
 /// A pair of values.
@@ skipping 29 matching lines @@
   Iterable<T> get items => _buffer.reversed;
 
   void add(T item) {
     _buffer.add(item);
 
     if (_buffer.length > capacity) {
       _buffer.removeAt(0);
     }
   }
 }