I've been looking at a bug reported for the Chinese site 56.com (what's up with China and all those numerical domain names – lucky numbers :)?) Here's a screenshot from a colleague, Opera on the left and Chrome on the right:
and it's a problem with how the line endings are encoded. The site's code contains typical Windows line endings (newline + carriage returns) but this regular expression assumes that innerHTML will contain newlines and not carriage returns. (This is the \n part of the regexp. The fix is simply replacing "\n" with "\n|\r".)
Firefox and Chrome return innerHTML with normalized LF line endings. IE and Opera return CRLF in this case, and comments are broken both in IE (8) and Opera for me.
Wow! The times they are a-changing..