Comment 28 for bug 1157732

After investigations and discussions with the various stakeholders (thanks Chris Coulson and Zoltan Balogh :), it was found that qtjsbackend is *only* used by QML. QML applications are written in javascript and therefore a javascript engine is needed to execute QML applications. V8 is the current choice of upstream and V8 is used to execute QML applications. QtWebKit's JavaScriptCore (JSC) engine is used by QtWebKit and any webkit widgets in QML applications, not V8. qtjsbackend is not exposed to unfiltered web content and therefore qtjsbackend can be promoted as is and we do not need a separate maintenance story for it. ACK

 (note: while a developer could theoretically write a QML application to subvert V8, it doesn't break a privilege boundary-- that developer could more easily write the app to do what he wants directly).