Neither I nor Wikipedia said "used wherever WebKit is used". The Wikipedia article said "JavaScript engine for WebKit implementations" and I said "part of WebKi

Neither I nor Wikipedia said "used wherever WebKit is used". The Wikipedia article said "JavaScript engine for WebKit implementations" and I said "part of WebKit". The fact that Chrome chooses not to use it is immaterial. It is part of WebKit. Check out the WebKit source and you will get the JavaScriptCore source as part of it. Similarly, there's a GIMP-based image editor called Seashore that doesn't use a lot of GIMP's UI, but I still think it's fair to say that the UI code is part of GIMP.