CopyUTF8toUCS2() is absent from nsReadableUtils.h CopyUCS2toUTF8() should be added as well.
re-targeting milestones, starting from a clean slate
Turns out that this is not needed now that we have Substring that has a constructor that takes two iterators, as scc explained to me. Making INVALID.
In case anyone cares, the signature for one of thise copy functions would have been CopyXXXtoYYY( sourceStartIter, sourceEndIter, destString ); but this is no better than saying destString = Substring(sourceStartIter, sourceEndIter); in fact ... it's worse in the current implementations of the |CopyXXXtoYYY|s that do exist, since they don't check for dependencies as assignment does. I've filed bug #81433 to get rid of the existing iterator-based |CopyXXXtoYYY| string functions (|CopyUnicodeTo| and |AppendUnicodeTo|).