Restricted mode warning when contributing a new extension

Note: the affect version needs to be refined

Reproductions steps

1. Install Extension Repository Server and Extension Repository Application
2. Go to Extension.WebHome
3. Fill the extension name field in the Contribute Extension... form.
4. Click Add
5. Observe the form

Expected

No warning message.

Actual

A security warning message is displayed at the top of the form (" For security reasons, the content of the edited document is executed in restricted mode, as the edit was not initiated by a validated request. There may be unexpected errors due to this.").