The anticlockwise parameter for CanvasRenderingContext2D.ellipse() is optional and has a default of false.

The spec reference is:
http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#dfnReturnLink-0

BUG=335124

Review URL: https://codereview.chromium.org/139173006

git-svn-id: svn://svn.chromium.org/blink/trunk@165260 bbb929c8-8fbe-4397-9dbb-9b2b20218538