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/mod.rs

@@ -10,7 +10,9 @@ mod transferable;
 
 use std::collections::HashMap;
 
-use base::id::{BlobId, DomExceptionId, DomPointId, ImageBitmapId, MessagePortId};
+use base::id::{
+    BlobId, DomExceptionId, DomPointId, ImageBitmapId, MessagePortId, OffscreenCanvasId,
+};
 use log::warn;
 use malloc_size_of_derive::MallocSizeOf;
 use serde::{Deserialize, Serialize};
@@ -38,6 +40,8 @@ pub struct StructuredSerializedData {
     pub image_bitmaps: Option<HashMap<ImageBitmapId, SerializableImageBitmap>>,
     /// Transferred image bitmap objects.
     pub transferred_image_bitmaps: Option<HashMap<ImageBitmapId, SerializableImageBitmap>>,
+    /// Transferred offscreen canvas objects.
+    pub offscreen_canvases: Option<HashMap<OffscreenCanvasId, TransferableOffscreenCanvas>>,
 }
 
 impl StructuredSerializedData {
@@ -48,6 +52,7 @@ impl StructuredSerializedData {
         match val {
             Transferrable::ImageBitmap => is_field_empty(&self.transferred_image_bitmaps),
             Transferrable::MessagePort => is_field_empty(&self.ports),
+            Transferrable::OffscreenCanvas => is_field_empty(&self.offscreen_canvases),
             Transferrable::ReadableStream => is_field_empty(&self.ports),
             Transferrable::WritableStream => is_field_empty(&self.ports),
             Transferrable::TransformStream => is_field_empty(&self.ports),