[0.31-beta.2] Disabling IME is broken on macOS

[nicoburns]

Description

On macOS ImeRequest::Disable is implemented as:

ImeRequest::Disable => {
    self.view().set_ime_allowed(None);
    return Ok(());
},

However the set_ime_allowed function is defined as:

pub(super) fn set_ime_allowed(&self, capabilities: Option<ImeCapabilities>) {
    if self.ivars().ime_capabilities.get().is_some() {
        return;
    }
    self.ivars().ime_capabilities.set(capabilities);

    if capabilities.is_some() {
        return;
    }

    // Clear markedText
    *self.ivars().marked_text.borrow_mut() = NSMutableAttributedString::new();

    if self.ivars().ime_state.get() != ImeState::Disabled {
        self.ivars().ime_state.set(ImeState::Disabled);
        self.queue_event(WindowEvent::Ime(Ime::Disabled));
    }
}

The guard at the very top of this function means that calling this function has no effect if IME is enabled (the macos backend appears to track this by whether the ime_capabilities is Some or None)

macOS version

macOS 15.6.1 (but OS version is unlikely to be relevant)

Winit version

0.31-beta.2