Declaration::lengthValue only supported 'px' sizes, but one can transform
any 'pt' value into 'px' by multiplying with 1.33.
Notes: this ignores display DPI, and instead follows the W3C definition
of 'pt' and 'px' as absolute lengths [1].
[1] https://www.w3.org/TR/css3-values/#absolute-lengths
1pt = 1/72th of 1 inch
1px = 1/96th of 1 inch
so the conversion is px = pt * (72/96).
Add unit test that verifies this using QPushButton's icon-sizes property,
also with changed font in preparation of adding support for 'em' and 'ex'
units in a follow up commit.
Task-number: QTBUG-8096
Pick-to: 6.2
Done-with: Cristian Maureira-Fredes <Cristian.Maureira-Fredes@qt.io>
Change-Id: I58782e7ad0e2ff9d89ed695f8a23b1e584cfed64
Reviewed-by: Andy Shaw <andy.shaw@qt.io>
a1a6e3d21b