Note that you have to be sure to recompile sgml-mode.el AND nxml-mode.el
after applying these patches, 'make' isn't smart enough to do it
automatically (yes, I figured this out the hard way).

>> <t>>1</t>
>>
>> (syntax-ppss) on the location of "1" in the above, gives (-1 ...).  And
>> then (syntax-ppss) on the "/" will give (0 ...).  So the syntax
>> propertize rule for quote use of (zerop (car (syntax-ppss))) no longer
>> works correctly to see whether it's inside or outside a tag.
>>
>> ">" outside of tags should be set to syntax ".", but I would assume that
>> adding a syntax-propertize rule which calls syntax-ppss for every ">"
>> (to check whether it's inside a tag or not) will be very slow, just like
>> calling it for every quote was.

Oh, I figured it out, we can just look at (nth 9 ppss), because the list
of open parens is still okay, regardless of unmatched close parens.