fix: browser detection

update browser detection logic:
detect either window or web worker (WorkerGlobalScope).

fixes firebase#8299 firebase#8284

.changeset/chilly-moons-play.md

@@ -0,0 +1,5 @@
+---
+'@firebase/util': patch
+---
+
+fix: browser detection (detect either window or web worker)

packages/util/src/environment.ts

@@ -18,6 +18,11 @@
 import { CONSTANTS } from './constants';
 import { getDefaults } from './defaults';
 
+/**
+ * Type placeholder for `WorkerGlobalScope` from `webworker`
+ */
+declare class WorkerGlobalScope {}
+
 /**
  * Returns navigator.userAgent string or '' if it's not defined.
  * @return user agent string
@@ -77,7 +82,18 @@ export function isNode(): boolean {
  * Detect Browser Environment
  */
 export function isBrowser(): boolean {
-  return typeof self === 'object' && self.self === self;
+  return typeof window !== 'undefined' || isWebWorker();
+}
+
+/**
+ * Detect Web Worker context
+ */
+export function isWebWorker(): boolean {
+  return (
+    typeof WorkerGlobalScope !== 'undefined' &&
+    typeof self !== 'undefined' &&
+    self instanceof WorkerGlobalScope
+  );
 }
 
 /**