void arc(
num x,
num y,
num radius,
num startAngle,
num endAngle,
[bool anticlockwise = false]
)

Not documented.

Source

@DomName('CanvasRenderingContext2D.arc')
void arc(num x,  num y,  num radius,  num startAngle, num endAngle,
    [bool anticlockwise = false]) {
  // TODO(terry): This should not be needed: dartbug.com/20939.
  _arc(x, y, radius, startAngle, endAngle, anticlockwise);
}