[TASK] Ensure login module is completely loaded and processed

Resolves: #91265
Releases: master, 9.5
Change-Id: I5e413f91ae92ba666a74606767c4ecd081407f79
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/64389
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>

Build/Sources/TypeScript/backend/Resources/Public/TypeScript/Login.ts

@@ -24,6 +24,7 @@ import 'TYPO3/CMS/Backend/Input/Clearable';
  */
 class BackendLogin {
   public options: any;
+  public ready: boolean = true;
 
   constructor() {
     this.options = {
@@ -43,8 +44,12 @@ class BackendLogin {
 
     // prevent opening the login form in the backend frameset
     if (top.location.href !== location.href) {
+      this.ready = false;
       top.location.href = location.href;
     }
+    if (this.ready) {
+      document.body.setAttribute('data-typo3-login-ready', 'true');
+    }
   }
 
   /**

composer.json

@@ -89,7 +89,7 @@
 		"phpstan/phpstan": "^0.12.13",
 		"rector/rector": "^0.7.14",
 		"typo3/cms-styleguide": "~10.0.2",
-		"typo3/testing-framework": "^6.2.3"
+		"typo3/testing-framework": "^6.2.4"
 	},
 	"suggest": {
 		"ext-gd": "GDlib/Freetype is required for building images with text (GIFBUILDER) and can also be used to scale images",