--- /dev/null
+/*! *****************************************************************************
+Copyright (c) Microsoft Corporation. All rights reserved.
+Licensed under the Apache License, Version 2.0 (the "License"); you may not use
+this file except in compliance with the License. You may obtain a copy of the
+License at http://www.apache.org/licenses/LICENSE-2.0
+
+THIS CODE IS PROVIDED ON AN *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
+WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
+MERCHANTABLITY OR NON-INFRINGEMENT.
+
+See the Apache Version 2.0 License for specific language governing permissions
+and limitations under the License.
+***************************************************************************** */
+
+
+
+/// <reference no-default-lib="true"/>\r
+
+
+interface WeakRef<T extends object> {\r
+ readonly [Symbol.toStringTag]: "WeakRef";\r
+\r
+ /**\r
+ * Returns the WeakRef instance's target object, or undefined if the target object has been\r
+ * reclaimed.\r
+ */\r
+ deref(): T | undefined;\r
+}\r
+\r
+interface WeakRefConstructor {\r
+ readonly prototype: WeakRef<any>;\r
+\r
+ /**\r
+ * Creates a WeakRef instance for the given target object.\r
+ * @param target The target object for the WeakRef instance.\r
+ */\r
+ new<T extends object>(target?: T): WeakRef<T>;\r
+}\r
+\r
+declare var WeakRef: WeakRefConstructor;\r
+\r
+interface FinalizationRegistry {\r
+ readonly [Symbol.toStringTag]: "FinalizationRegistry";\r
+\r
+ /**\r
+ * Registers an object with the registry.\r
+ * @param target The target object to register.\r
+ * @param heldValue The value to pass to the finalizer for this object. This cannot be the\r
+ * target object.\r
+ * @param unregisterToken The token to pass to the unregister method to unregister the target\r
+ * object. If provided (and not undefined), this must be an object. If not provided, the target\r
+ * cannot be unregistered.\r
+ */\r
+ register(target: object, heldValue: any, unregisterToken?: object): void;\r
+\r
+ /**\r
+ * Unregisters an object from the registry.\r
+ * @param unregisterToken The token that was used as the unregisterToken argument when calling\r
+ * register to register the target object.\r
+ */\r
+ unregister(unregisterToken: object): void;\r
+}\r
+\r
+interface FinalizationRegistryConstructor {\r
+ readonly prototype: FinalizationRegistry;\r
+\r
+ /**\r
+ * Creates a finalization registry with an associated cleanup callback\r
+ * @param cleanupCallback The callback to call after an object in the registry has been reclaimed.\r
+ */\r
+ new(cleanupCallback: (heldValue: any) => void): FinalizationRegistry;\r
+}\r
+\r
+declare var FinalizationRegistry: FinalizationRegistryConstructor;\r