Regression in <sup> and <sub> tag behaviour between QtDeclarative and QtQuick

If I run the attached qml file with ~/Qt5.3.2/5.3/gcc_64/bin/qmlviewer subscript.qml , I get the output qmlviewer_supsub.png.

If I update the file to be import QtQuick 2.2 instead, and run ~/Qt5.3.2/5.3/gcc_64/bin/qmlscene subscript.qml, I get the output qmlscene_supsub.png.

In my opinion (and that of various people who've noticed changes in an application originally built on Qt4.8 and QtDeclarative and now ported to Qt5 and QtQuick), the old qmlviewer (ie QtDeclarative) is a quite a bit nicer than qmlscene's presentation of sup and sub (well actually the qmlscene <sup> is quite clearly defective in comparison).

I haven't verified it myself, but I believe the issue is the same on MacOS and iOS QML engines.

Sorry if this is a duplicate of QTBUG-24621 or QTBUG-32948, but neither of those mention the regression in behaviour from the QtDeclarative world.

<sup> and <sub> are listed in the supported HTML subset.

(I also note it's possible to do some very limited subscripting/superscripting with unicode things like '²' and '₂'; these do work and don't change between qmlviewer/qmlscene... but don't actually look as good as QDeclarative's <sup> and <sub> did.)