message: fix another discrepancy with HTML5 arcTo
  HTML5's arcTo does not draw a line from the end of the arc to `b`, so
  this should not either.
diff: @@ -42,9 +42,16 @@ impl Builder {
  /// Adds a circular arc to the [`Path`] with the given control points and
  /// radius.
  ///
  - /// This essentially draws two straight line segments, from the current
  - /// position to `a`, and from `a` to `b`, but smooths out the corner by
  - /// fitting a circular arc of `radius` tangent to both segments.
  + /// This essentially draws a straight line segment from the current
  + /// position to `a`, but fits a circular arc of `radius` tangent to that
  + /// segment and tangent to the line between `a` and `b`.
  + ///
  + /// With another `.line_to(b)`, the result will be a path connecting the
  + /// starting point and `b` with straight line segments towards `a` and a
  + /// circular arc smoothing out the corner at `a`.
  + ///
  + /// See [the HTML5 specification of `arcTo`](https://html.spec.whatwg.org/multipage/canvas.html#building-paths:dom-context-2d-arcto)
  + /// for more details and examples.
  pub fn arc_to(&mut self, a: Point, b: Point, radius: f32) {
  use lyon::{math, path};
  @@ -53,7 +60,7 @@ impl Builder {
  let end = math::Point::new(b.x, b.y);
  if start == mid || mid == end || radius == 0.0 {
  - let _ = self.raw.line_to(end);
  + let _ = self.raw.line_to(mid);
  return;
  }
  @@ -62,7 +69,7 @@ impl Builder {
  + end.x * (start.y - mid.y);
  if double_area == 0.0 {
  - let _ = self.raw.line_to(end);
  + let _ = self.raw.line_to(mid);
  return;
  }
  @@ -91,8 +98,6 @@ impl Builder {
  },
  arc_end,
  );
  -
  - let _ = self.raw.line_to(end);
  }
  /// Adds an ellipse to the [`Path`] using a clockwise direction.
  