Qiantan Hong suggested that Emacs should enable sandboxing in WebKit, for all the usual security reasons. (Thanks, Qiantan!) Attached is a proposed patch to implement that suggestion; it's a bit fancier than what Qiantan originally proposed in because it checks that WebKit 2.26 or later is in use, and it avoids a duplicate call to webkit_web_context_get_default. I'm cc'ing this to Qiantan and to other recent committers to xwidget.c, to get their opinions.