object converted to iframe even when iframe is part invalid elements.

[cedric-anne]

📝 Provide detailed reproduction steps (if any)

1. Initialize a TinyMCE instance with both convert_unsafe_embeds: true and invalid_elements: 'applet,canvas,form,iframe' options.
2. Paste a piece of HTML that contains an <object> tag that is neither an image, neither a video, neither an audio, for instance, you can paste the default output from this example: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/object#try_it .

https://fiddle.tiny.cloud/MezUb2kZ3Y/1

✔️ Expected result

The unsafe <object> is discarded, as <iframe> is an invalid element.

❌ Actual result

The unsafe <object> is converted to an <iframe>.

📃 Other details

• Browser: Google Chrome Version 123.0.6312.58
• OS: Ubuntu 22.04
• First affected version: reproduced in 6.8.3
• Worked in version: works as expected in 7.0.0