Fix#1284, which was closed as stale in 2019, but which I will now reopen. Html Reader converts *Unicode* whitespace characters in a DOM text node to space. However, Html treats only space, tab, CR, LF, vertical tab, and form-feed as whitespace. Using a regular expression with the `u` (Unicode) modifier causes a number of other characters to be converted to space inappropriately. The issue mentions "ideographic space" in particular, stating that it is used for formatting and should be preserved. "Non-breaking space" is also used in the same way and should also be preserved. An exception is made for a text node consisting of a single non-breaking space, since that is used as a placeholder by Html Writer; my own guess is that this is the reason why the Unicode modifier was used in the first place.
oleibman