bug(Dialog): Dialog loses focus when it doesn't contain any focusable elements

[sciambalala]

Is this a regression?

• Yes, this behavior used to work in the previous version

The previous version in which this bug was not present was

No response

Description

Tab and Shift + Tab move focus outside the dialog when there are no focusable elements inside it.

Reproduction

StackBlitz link: https://stackblitz.com/edit/3l8tbmvh?file=src%2Fexample%2Fcdk-dialog-data-example.ts
Steps to reproduce:

1. Navigate to the "Open dialog" button with the keyboard and press Enter.
2. Press either Tab or Shift + Tab.

Expected Behavior

Tab and Shift + Tab do not move focus outside the dialog.

Actual Behavior

Tab and Shift + Tab move focus outside the dialog.

Environment

• Angular: v22
• CDK/Material: v22
• Browser(s): any
• Operating System (e.g. Windows, macOS, Ubuntu): any