Function conic_gradient_pattern 

pub fn conic_gradient_pattern(
    center: LayoutPoint,
    scale: DeviceVector2D,
    angle: f32,
    start_offset: f32,
    end_offset: f32,
    extend_mode: ExtendMode,
    stops: &[GradientStop],
    gpu_buffer_builder: &mut GpuBufferBuilder,
) -> Pattern