feat: Add an owned display handle type

This was supposed to be rolled out with the rwh v0.6 update, but it
was left behind for some reason. I've added this type back.

Signed-off-by: John Nunley <dev@notgull.net>

src/platform_impl/web/event_loop/mod.rs

@@ -12,8 +12,8 @@ pub(crate) mod runner;
 mod state;
 mod window_target;
 
-pub use proxy::EventLoopProxy;
-pub use window_target::EventLoopWindowTarget;
+pub(crate) use proxy::EventLoopProxy;
+pub(crate) use window_target::{EventLoopWindowTarget, OwnedDisplayHandle};
 
 pub struct EventLoop<T: 'static> {
     elw: RootEventLoopWindowTarget,

src/platform_impl/web/event_loop/window_target.rs

@@ -704,4 +704,27 @@ impl EventLoopWindowTarget {
     pub(crate) fn waker(&self) -> Waker<Weak<Execution>> {
         self.runner.waker()
     }
+
+    pub(crate) fn owned_display_handle(&self) -> OwnedDisplayHandle {
+        OwnedDisplayHandle
+    }
+}
+
+#[derive(Clone)]
+pub(crate) struct OwnedDisplayHandle;
+
+impl OwnedDisplayHandle {
+    #[cfg(feature = "rwh_05")]
+    #[inline]
+    pub fn raw_display_handle_rwh_05(&self) -> rwh_05::RawDisplayHandle {
+        rwh_05::WebDisplayHandle::empty().into()
+    }
+
+    #[cfg(feature = "rwh_06")]
+    #[inline]
+    pub fn raw_display_handle_rwh_06(
+        &self,
+    ) -> Result<rwh_06::RawDisplayHandle, rwh_06::HandleError> {
+        Ok(rwh_06::WebDisplayHandle::new().into())
+    }
 }