In bug 1210517, I'm eliminating all calls to do_CreateInstance(NS_VARIANT_CONTRACTID) in favor of calling new nsVariant() directly. The one remaining instance after the patch in that bug is in CreateVoidVariant, because I didn't want to add a new #include to nsGlobalWindow.h. The easiest fix is probably to outline CreateVoidVariant into nsGlobalWindow.cpp. If the performance is even actually an issue here, you'd still be replacing a virtual call with a static one, so I'd think you'd still be ahead. I'm not really sure why this little method actually even exists. It looks like bholley added it in bug 860941.

I also eliminated the static because a static method in a header seems weird. try run: https://treeherder.mozilla.org/#/jobs?repo=try&revision=ea2d0d9c982e

Comment on attachment 8670820 [details] [diff] [review] Outline CreateVoidVariant and create the variant directly. How about you make CreateVoidVariant a static method in nsGlobalWindow.cpp and put DialogValueHolder::Get() out of line? r=me with that

(In reply to Boris Zbarsky [:bz] from comment #2) > How about you make CreateVoidVariant a static method in nsGlobalWindow.cpp > and put DialogValueHolder::Get() out of line? That's a lot nicer; thanks for the suggestion.