Fix Servo IOSurface orientation and resize identity

crates/ely_servo_host/src/iosurface_handle.rs

@@ -16,10 +16,11 @@
 /// a Metal texture without copying pixels.
 ///
 /// `surface_id` is the stable surfman `SurfaceID` (a pointer-shaped
-/// `usize` widened to `u64` for the wire). It lets the receiver dedup:
-/// when two consecutive frames carry the same `surface_id` the
-/// imported `MTLTexture` is reused without re-importing. `width` and
-/// `height` are reported in surface pixels (post-DPR).
+/// `usize` widened to `u64` for the wire). Together with `width` and
+/// `height` it lets the receiver dedup imported IOSurfaces. The pixel
+/// dimensions are part of the identity because a resize can reuse the
+/// same surfman id for a newly-sized IOSurface. `width` and `height`
+/// are reported in surface pixels (post-DPR).
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 #[cfg_attr(feature = "servo-engine", derive(serde::Serialize, serde::Deserialize))]
 pub struct IOSurfaceHandle {
@@ -33,9 +34,15 @@ pub struct IOSurfaceHandle {
 /// "same surface as last frame" from "resize/swap rotated to a new
 /// surface" without minting a fresh mach port (mach ports are a scarce
 /// kernel resource and `IOSurfaceCreateMachPort` is not cheap).
-#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
 pub struct IOSurfaceIdentity {
     pub surface_id: u64,
     pub width: u32,
     pub height: u32,
 }
+
+impl IOSurfaceIdentity {
+    pub fn from_handle(handle: IOSurfaceHandle) -> Self {
+        Self { surface_id: handle.surface_id, width: handle.width, height: handle.height }
+    }
+}