Merge more Kernel infrastructure from kernel_sdk SDK fork.

runtime/lib/compact_hash.dart

Index: runtime/lib/compact_hash.dart
diff --git a/runtime/lib/compact_hash.dart b/runtime/lib/compact_hash.dart
index 9912d07f2afb02bdc35f7642c785e34832e7ceaa..86ec9d83acf8362b2944173e910c5db56faffd28 100644
--- a/runtime/lib/compact_hash.dart
+++ b/runtime/lib/compact_hash.dart
@@ -2,9 +2,6 @@
 // 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;
-
 // Hash table with open addressing that separates the index from keys/values.
 
 abstract class _HashFieldBase {