See comments in bug 241392. I just did a mozilla.org search on serializeToString and came up with http://www.google.com/custom?hl=en&lr=&ie=UTF-8&oe=UTF-8&cof=AWFID%3A9262c37cefe23a86%3BL%3Ahttp%3A%2F%2Fwww.mozilla.org%2Fimages%2Fmozilla-banner.gif%3BLH%3A58%3BLW%3A600%3BBGC%3Awhite%3BT%3Ablack%3BLC%3A%23990000%3BVLC%3Apurple%3BALC%3A%230000ff%3BGALT%3A%23666633%3BGFNT%3Agrey%3BGIMP%3A%23cc0000%3BAH%3Acenter%3B&domains=mozilla.org&q=serializeToString&btnG=Google+Search&sitesearch=mozilla.org which is not helpful in the least. Something to look into for devmo.
This bug has been buried in the graveyard and has not been updated in over 5 years. It is probably safe to assume that it will never be fixed, so resolving as WONTFIX. [Mass-change filter: graveyard-wontfix-2014-09-24]