[whatwg] bezierCurveTo summary is incorrect

[Oliver Hunt]

Just noticed while looking at the path modification functions that the  
summary of bezierCurveTo (at the beginning of Section 4.8.11.1.8)  
gives bezierCurveTo the signature "bezierCurveTo(cpx, cpy, x, y)"  
which is the signature for quadraticCurveTo.  The signature should be  
"bezierCurveTo(cp1x, cp1y, cp2x, cp2y, x, y)"

--Oliver