When inserting a new utf-16 surrogate next to an existing surrogate
with replaceData, the surrogates would not get merged correctly into a
single code point. This is because internally the text data is stored
as utf-8, and the two surrogates would be converted seperately. This
has now been fixed by first recreating the whole string in utf-16 and
then converting it back to utf-8.
It's not the most efficient solution, but this fixes at least 6 WPT
subtests.
CDATASection inherits from Text, and so it was incorrect for them to
claim not to be Text nodes.
This fixes at least two WPT subtests. :^)
It also exposed a bug in the DOM Parsing and Serialization spec,
where we're not told how to serialize CDATASection nodes.
Spec bug: https://github.com/w3c/DOM-Parsing/issues/38