https://bugs.winehq.org/show_bug.cgi?id=38189
--- Comment #11 from Jacek Caban jacek@codeweavers.com --- Thanks for the research. In quoted DocumentComplete Load() is called before setting charset, but the actual loading is asynchronous, so it makes sense. I guess we could use nsIContentViewer::GetHintCharacterSet or nsIDocShell::SetForceCharset to support that, but I'd prefer to avoid messing with those without a real test case (one that really needs true implementation).
A succeeding stub seems good enough for now. I will send a patch.