It'd be useful for building webpages internal to embedding applications if WebKit.WebView had a method for loading and displaying a webpage from a GIO InputStream, just like it already supports loading from a string, GBytes, URIRequest, or uri.
There's currently no way to load from data sending chunks to the web process, so if we add load_from_stream we would have to read the whole stream and then use load_from_gbytes, something applications can do as well. The only way would be registering a custom uri scheme and loading the data that way.
I understand. I was trying to avoid these ugly work-arounds, so I'll do some more research and report the issue to the right subproject. Then someone (possibly me) can fix the issue here in the GTK layer.
While I found the WebCore code that could be changed to accomodate this feature, the patch to do so would either have to bypass a lot of logic or make significant changes to complex code. As such the hacks described previously are probably the cleanest way to do this.