http://bugs.winehq.org/show_bug.cgi?id=48006
--- Comment #59 from Andrew Church achurch+wine@achurch.org --- (In reply to Sophira from comment #54)
I'm at a bit of a loss. I also can't explain why the webview did not auto-install for you.
On this point, the patch 7.21 release notes mention a change in the launcher to use WebView2, so it looks like you might have been part of a random trial. I haven't tried updating yet but we'll see what happens...