`stop-redirecting-in-notification-bar` automatically when possible

As discussed in https://github.com/sindresorhus/refined-github/issues/2952 and https://github.com/sindresorhus/refined-github/pull/3036

I think stop-redirecting-in-notification-bar can be done automatically if the user opened the notification in a new tab.

For example:

1. disable automatic redirect for all buttons, always
2. try calling history.back() (unless alt is pressed)

If you opened the notification in a new tab, history.back() won’t have any effect.

IMHO this makes sense since in that case, the notifications list is still open in its own tab.

PR welcome if you test that this works as expected in both browsers.

cc @FloEdelmann @karlhorky @tonglil

[karlhorky]

Got it, so something like the following?

function handleClick(event: delegate.Event<MouseEvent, HTMLButtonElement>): void {
    // Disable the redirect to the Notifications inbox if either:
    // 1. The alt key was held down during click
    // 2. The notification has been opened in a new tab
    const redirectDisabled = event.alt || sessionStorage.rghIsNewTab;
    event.delegateTarget.form!.toggleAttribute('data-redirect-to-inbox-on-submit', !redirectDisabled);
    delete sessionStorage.rghIsNewTab;
}

async function init(): Promise<void> {
    // If the history length is `1` on init, the
    // notification has been opened in a new tab
    sessionStorage.rghIsNewTab = history.length === 1;
	delegate(document, '.notification-shelf .js-notification-action button', 'click', handleClick);
}

[karlhorky]

Another option would be to leave all of the existing code as it is, and only add the condition of history.length === 1.

So something like:

function handleClick(event: delegate.Event<MouseEvent, HTMLButtonElement>): void {
    // Disable the redirect to the Notifications inbox if either:
    // 1. The alt key was held down during click
    // 2. The history length is `1` (a new tab)
    const redirectDisabled = event.alt || history.length === 1;
    event.delegateTarget.form!.toggleAttribute('data-redirect-to-inbox-on-submit', !redirectDisabled);
}