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

runtime/lib/core_patch.dart

Index: runtime/lib/core_patch.dart
diff --git a/runtime/lib/core_patch.dart b/runtime/lib/core_patch.dart
index f06c98b29efde22412d8961601237525e931603c..29357aec4d8fe7c873d5323cb5646c592c3cf382 100644
--- a/runtime/lib/core_patch.dart
+++ b/runtime/lib/core_patch.dart
@@ -2,8 +2,13 @@
 // 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:async";
+import "dart:collection" show LinkedList, LinkedListEntry;
+import 'dart:convert' show ASCII, JSON;
+import "dart:isolate";
 import "dart:math";
 import "dart:typed_data";
+import 'dart:_internal' as internal;
 
 // Equivalent of calling FATAL from C++ code.
 _fatal(msg) native "DartCore_fatal";