Comment 3 for bug 1959032

Looking into the issues with dashes, this broke from the changes for bug 1922470

The different line cap styles have quite different behaviour in combination with dashes (https://www.cairographics.org/manual/cairo-cairo-t.html#cairo-set-dash), e.g. a length of 0.0 can actually draw a square

We could either find an alternative fix for the previous issue, or adjust how the dash patterns are translated to cairo to accommodate the line cap style.