Use document instead of window for browser detection

GJS defines `window` as an alias for `globalThis`, but it isn't a
real browser.

Author: amezin

spec/core/baseSpec.js

@@ -11,7 +11,7 @@ describe('base helpers', function() {
     });
 
     it('returns true for an Error that originated from another frame', function() {
-      if (typeof window === 'undefined') {
+      if (typeof document === 'undefined') {
         pending('This test only runs in browsers.');
       }
 

spec/core/integration/EnvSpec.js

@@ -1,6 +1,6 @@
 describe('Env integration', function() {
   let env;
-  const isBrowser = typeof window !== 'undefined';
+  const isBrowser = typeof document !== 'undefined';
   const queueMicrotask =
     globalThis.queueMicrotask ??
     function(fn) {

spec/core/integration/GlobalErrorHandlingSpec.js

@@ -1,5 +1,5 @@
 describe('Global error handling (integration)', function() {
-  const isBrowser = typeof window !== 'undefined';
+  const isBrowser = typeof document !== 'undefined';
   const queueMicrotask =
     globalThis.queueMicrotask ??
     function(fn) {

spec/core/jasmineNamespaceSpec.js

@@ -105,7 +105,7 @@ describe('The jasmine namespace', function() {
       'getGlobal'
     ]);
 
-    if (typeof window !== 'undefined') {
+    if (typeof document !== 'undefined') {
       // jasmine-html.js
       result.add('HtmlReporterV2');
       result.add('HtmlReporterV2Urls');