[DevTools] chore: extract pure functions from fiber/renderer.js (facebook#35924)

I am in a process of splitting down the renderer implementation into
smaller units of logic that can be reused. This change is about
extracting pure functions only.

Author: hoxyq

packages/react-devtools-shared/src/backend/DevToolsNativeHost.js

@@ -0,0 +1,64 @@
+/**
+ * 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
+ */
+
+import type {HostInstance} from './types';
+
+// Some environments (e.g. React Native / Hermes) don't support the performance API yet.
+export const getCurrentTime: () => number =
+  // $FlowFixMe[method-unbinding]
+  typeof performance === 'object' && typeof performance.now === 'function'
+    ? () => performance.now()
+    : () => Date.now();
+
+// Ideally, this should be injected from Reconciler config
+export function getPublicInstance(instance: HostInstance): HostInstance {
+  // Typically the PublicInstance and HostInstance is the same thing but not in Fabric.
+  // So we need to detect this and use that as the public instance.
+
+  // React Native. Modern. Fabric.
+  if (typeof instance === 'object' && instance !== null) {
+    if (typeof instance.canonical === 'object' && instance.canonical !== null) {
+      if (
+        typeof instance.canonical.publicInstance === 'object' &&
+        instance.canonical.publicInstance !== null
+      ) {
+        return instance.canonical.publicInstance;
+      }
+    }
+
+    // React Native. Legacy. Paper.
+    if (typeof instance._nativeTag === 'number') {
+      return instance._nativeTag;
+    }
+  }
+
+  // React Web. Usually a DOM element.
+  return instance;
+}
+
+export function getNativeTag(instance: HostInstance): number | null {
+  if (typeof instance !== 'object' || instance === null) {
+    return null;
+  }
+
+  // Modern. Fabric.
+  if (
+    instance.canonical != null &&
+    typeof instance.canonical.nativeTag === 'number'
+  ) {
+    return instance.canonical.nativeTag;
+  }
+
+  // Legacy.  Paper.
+  if (typeof instance._nativeTag === 'number') {
+    return instance._nativeTag;
+  }
+
+  return null;
+}