MSIE document.charset and document.defaultCharset are not supported in WebKit, see the bug URL. Firefox document.characterSet is also not supported, see the attached test case. document.charset and document.characterSet are apparently supposed to be read/write, not sure about document.defaultCharset.
Created attachment 4672 [details] test case
Created attachment 4821 [details] proposed patch Implements: 1) document.charset (MSIE, read-write) 2) document.defaultCharset (MSIE, read-only) 3) document.characterSet (Firefox, read-only) 4) document.actualEncoding (Firefox, old DOM3 drafts, read-only) 5) document.inputEncoding (actualEncoding was renamed so in DOM3; Firefox doesn't support this yet). Of related properties, doesn't implement xmlEncoding (also in DOM3) and entity.inputEncoding.
Comment on attachment 4821 [details] proposed patch I think that the Charset setting code should use UTF8String() instead of cstring(). The patch looks otherwise perfect, so I'm going to mark it review+ anyway, since cstring() seems OK.
Created attachment 4828 [details] Patch using UTF8String() Replaced cstring() with UTF8String()
Just noticed that dom/xhtml/level3/core/documentgetinputencoding01 now succeeds:-)
Verified (but the committed patch doesn't use UTF8String(), nor updates dom/xhtml/level3/core/ documentgetinputencoding01 results).