Bug 237403

Summary: Can't transfer an ImageBitmap through a MessageChannel
Product: WebKit Reporter: Kaiido <tristan.fraipont>
Component: CanvasAssignee: Nobody <webkit-unassigned>
Status: NEW ---    
Severity: Normal CC: cdumez, dino, heycam, kkinnunen, sabouhallawa, simon.fraser, webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: Safari Technology Preview   
Hardware: Unspecified   
OS: Unspecified   

Description Kaiido 2022-03-02 18:54:53 PST 
Transferring an ImageBitmap through the ports of a MessageChannel makes the `data` of the MessageEvent `null`.  
This doesn't happen when only cloning the ImageBitmap instead of transferring it. This also doesn't happen when transferring from a Worker's `postMessage` (this is being tested by WPT), nor when transferred from an WindowProxy, i.e this only concerns MessageChannel.

You can see a minimal repro at https://jsfiddle.net/1kzxvad9/
Comment 1 Radar WebKit Bug Importer 2022-03-09 18:55:15 PST 
<rdar://problem/90072516>