Change 997fd3b88e fixed integer overflows
with huge texts. This was done by using qsizetype for size calculations
instead of int. However, that change introduced a serious regression
due to an itermediate imultiplication result being "promoted" to unsigned,
and therefore a negative value being converted to a large positive.
The solution is to make sure all values in the expression are signed.
Fixes: QTBUG-123339
Task-number: QTBUG-119611
Pick-to: 6.7
Change-Id: I3f9189f77b383c6103cf5b35981cdb607b065f6f
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>
7a84c58f55