Fix Sequential Iterator assert on invalid rectangles
Summary:
Before Quick Brush engine (roundmarker) was crashing
because Sequential Iterator throwed out asserts
when the rectangle was not "empty" according to Qt
but still not valid (for example has intmin value on
width or height). This commit fixes that behaviour by
providing additional checks.
Commit includes also benchmarks for roundmarker.
BUG:404179
Test Plan:
- benchmarks included in the commit
- painting with Quick Brush (i.e. b) Basic-1)
with size <1 px
Reviewers: dkazakov, Krita
Reviewed By: dkazakov, Krita
Subscribers: rempt
Tags: Krita
Differential Revision: https://phabricator.kde.org/D19881