Binding Text width to implicitWidth can result in incorrect layout

If the text is not left aligned and the width changes during layout due
to implictWidth changing, the text needs to be laid out again.

Task-number: QTBUG-40161
Change-Id: I1ad679ccdc5595dd749600abe08ed46ac179d7bf
Reviewed-by: Andrew den Exter <andrew.den.exter@qinetic.com.au>