Migrates off getInstrumentedStats' deprecated fields

Summary:
This diffs replaces uses of the deprecated fields from HermesInternal.getInstrumentedStats() with the ones from Hermes' TimedRuntime.

Changelog:
[General][Added] - JSITimerInternal descriptor

Reviewed By: rubennorte

Differential Revision: D36625701

fbshipit-source-id: fbdb554e5cfb0b3556fcbe01f9e2930ace66a619

flow/JSITimerInternalType.js

@@ -0,0 +1,30 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow strict
+ * @format
+ */
+
+// Declarations for functionality exposed by Hermes' TimerStats decorator.
+//
+// For backwards-compatibility, code that uses such functionality must also
+// check explicitly at run-time whether the object(s) and method(s) exist, and
+// fail safely if not.
+
+/**
+ * JSITimerInternalType is the global object installed by Hermes' TimedRuntime
+ * decorator, and it is used to extract runtime timing information.
+ */
+declare type $JSITimerInternalType = {
+  /**
+   * Returns the counters that TimedRuntime keep track.
+   * There are no guarantees about what keys exist in it, but they can be
+   * printed for informational purposes.
+   * @return An object that maps strings to various types of performance
+   *    statistics.
+   */
+  +getTimes?: () => {[string]: number | string, ...},
+};