canvas: Make OffscreenCanvas transferable (without placeholder) (#37872)

Follow the specification and make OffscreenCanvas objects are
transferable,
but not in case if there are a weak reference to placeholder canvas
element.
To handle it properly need to implement dedicated frame
provider/dispatcher
between canvas element (script thread) and offscreen canvas (dedicated
worker thread).

https://html.spec.whatwg.org/multipage/#the-offscreencanvas-interface:transferable-objects

Testing: Improvements in the following tests
-
html/canvas/element/drawing-images-to-the-canvas/2d.drawImage.detachedcanvas.html
-
html/canvas/offscreen/manual/convert-to-blob/offscreencanvas.convert.to.blob*
-
html/canvas/offscreen/manual/the-offscreen-canvas/offscreencanvas.transfer*
-
html/infrastructure/safe-passing-of-structured-data/transfer-errors.window.js

Part of #24276

Signed-off-by: Andrei Volykhin <andrei.volykhin@gmail.com>

components/shared/constellation/structured_data/transferable.rs

@@ -28,6 +28,8 @@ pub enum Transferrable {
     ImageBitmap,
     /// The `MessagePort` interface.
     MessagePort,
+    /// The `OffscreenCanvas` interface.
+    OffscreenCanvas,
     /// The `ReadableStream` interface.
     ReadableStream,
     /// The `WritableStream` interface.
@@ -185,3 +187,12 @@ impl MessagePortImpl {
         self.state = MessagePortState::Detached;
     }
 }
+
+#[derive(Debug, Deserialize, MallocSizeOf, Serialize)]
+/// A struct supporting the transfer of OffscreenCanvas, which loosely
+/// corresponds to the dataHolder in
+/// <https://html.spec.whatwg.org/multipage/#the-offscreencanvas-interface:offscreencanvas-16>
+pub struct TransferableOffscreenCanvas {
+    pub width: u64,
+    pub height: u64,
+}