Revert "Reland "Merge more Kernel infrastructure from kernel_sdk SDK fork.""

runtime/lib/collection_patch.dart

 // Copyright (c) 2013, 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.
 
-import 'dart:typed_data';
-import 'dart:_internal' as internal;
-
 @patch class HashMap<K, V> {
   @patch factory HashMap({ bool equals(K key1, K key2),
-                           int hashCode(K key),
-                           bool isValidKey(potentialKey) }) {
+                                 int hashCode(K key),
+                                 bool isValidKey(potentialKey) }) {
     if (isValidKey == null) {
       if (hashCode == null) {
         if (equals == null) {
           return new _HashMap<K, V>();
         }
         hashCode = _defaultHashCode;
       } else {
         if (identical(identityHashCode, hashCode) &&
             identical(identical, equals)) {
           return new _IdentityHashMap<K, V>();
@@ skipping 950 matching lines @@
       if (equals == null) {
         equals = _defaultEquals;
       }
     }
     return new _CompactLinkedCustomHashSet<E>(equals, hashCode, isValidKey);
   }
 
   @patch factory LinkedHashSet.identity() =
       _CompactLinkedIdentityHashSet<E>;
 }