Implements arc-to according to the SVG spec.
All coordinates are given relative to the current point.
This is the relative version of gsk.path_builder.PathBuilder.svgArcTo.
X radius
Y radius
the rotation of the ellipsis
whether to add the large arc
whether to sweep in the positive direction
the X coordinate of the endpoint
the Y coordinate of the endpoint
Implements arc-to according to the SVG spec.
All coordinates are given relative to the current point.
This is the relative version of gsk.path_builder.PathBuilder.svgArcTo.