So,  alerts true, and  alerts false. Heycam says that he updated the spec in  so that instanceof should be scope-agnostic. This is kind of unexpected, since I'd imagine that these two cases would look the same under the hood: we should end up in the compartment of the constructor, with the object being a cross-compartment wrapper.  http://bit.ly/14Tde2J  http://bit.ly/12XLbxI  http://dev.w3.org/2006/webapi/WebIDL/#es-interface-hasinstance
Oh, this is just bug 870423. /me facepalms
Wait, why? There is no sandbox here...
Oh, I see. The key is having the RHS be a proxy of any kind.... I guess we tested it for cases when the _LHS_ was the proxy, but not the other. Funtimes.
(In reply to Boris Zbarsky (:bz) from comment #3) > Oh, I see. The key is having the RHS be a proxy of any kind Well, a function proxy.