See bug 702353 comment 10. We can't do this reliably until we fix bug 673468.

Attaching the patch for posterity. Should be ready to land once weakmaps do the right thing in the wrapper case.

Comment on attachment 589073 [details] [diff] [review] patch v1 Looks like the dependent bug was fixed. Flagging mrbkap for review.

Pushed to try: https://tbpl.mozilla.org/?tree=Try&rev=6368d51f5470

Looks good - pushed to m-i: http://hg.mozilla.org/integration/mozilla-inbound/rev/f9145dab4be9

Backed out due to bug 731442: http://hg.mozilla.org/mozilla-central/rev/75fcd465d506

I don't know if this bug or the other bug is the place to discuss that, but basically the problem is that only native classes that are wrapper caches that preserve their wrapper can be used as weak map keys. The warning in question is at this line: http://mxr.mozilla.org/mozilla-central/source/js/src/jsweakmap.cpp#292 The actual callback function is here: http://mxr.mozilla.org/mozilla-central/source/js/xpconnect/src/XPCJSRuntime.cpp#1996 Notice that we don't actually allow all wrapper cache classes as weak map keys. This is because there are some wrapper caches that don't preserve their wrapper. Right now, we only allow nsINodes because that seemed like the most common thing people would use.