Remove syn 0.15 from our crate graph (fixes #24421)

This required bumps of:

* gleam
* image
* rust-webvr
* webrender
* webxr

components/canvas/canvas_data.rs

@@ -942,8 +942,7 @@ impl<'a> CanvasData<'a> {
             stride: None,
             format: webrender_api::ImageFormat::BGRA8,
             offset: 0,
-            is_opaque: false,
-            allow_mipmaps: false,
+            flags: webrender_api::ImageDescriptorFlags::empty(),
         };
         let data = self.drawtarget.snapshot_data_owned();
         let data = webrender_api::ImageData::Raw(Arc::new(data));