intl.accept_charsets doesn't seem to be used anymore, we should remove it? http://mxr.mozilla.org/mozilla-central/source/modules/libpref/src/init/all.js#990, mxr search is http://mxr.mozilla.org/mozilla-central/search?string=accept_charsets
See also bug 572652. It appears to me that it's long since obsolete.
This has now been removed by bug 572652. The only remnant for the MXR search http://mxr.mozilla.org/mozilla-central/search?string=accept_charsets is: http://mxr.mozilla.org/mozilla-central/source/js/src/tests/e4x/Regress/regress-308111.js#310 ...which is just from a testcase for an unrelated bug, so can remain.