[whatwg] Canvas 2d methods

[Benjamin Joffe]

Each of the methods defined for the canvas 2d context return null. I think it would be very convenient if instead they would return a reference to the 2d context for that canvas. This would allow writing such code as ctx.fill ().stroke() or ctx.moveTo(0,0).lineTo(10,10). This is how many of the native string and array methods work in _javascript_.