I did not do is width()/minWidth() => calcValue()/calcMinValue()
 as it is a bit tricky.
.merge some work bringing better precision to percentage calculations.

Combined with Web Fonts, this let us get rid of the red square+purple 'X'
at the top right of acid3.

CCBUG: 156947

svn path=/trunk/KDE/kdelibs/; revision=965865