Add support for new canvas ellipse method.

LayoutTests/fast/canvas/script-tests/canvas-arc-connecting-line.js

 description("Test that canvas arc()s are connected by a straight line. There should be two C-shapes with a line from the bottom of the left one to the top of the right one.");
 
 var canvas = document.createElement('canvas');
 document.body.appendChild(canvas)
 canvas.setAttribute('width', '300');
 canvas.setAttribute('height', '300');
 var ctx = canvas.getContext('2d');
-function deg2rad(x) {
-  return x * 3.141592653589 / 180;
-}
 ctx.fillStyle = '#0f0';
 ctx.fillRect(0, 0, canvas.width, canvas.height);
 ctx.lineJoin = 'bevel';
 ctx.lineWidth = 12;
 ctx.beginPath();
-ctx.arc(200, 50, 40, deg2rad(90), deg2rad(-90), false);
-ctx.arc(100, 50, 40, deg2rad(90), deg2rad(-90), false);
+ctx.arc(200, 50, 40, Math.PI / 2, -Math.PI / 2, false);
+ctx.arc(100, 50, 40, Math.PI / 2, -Math.PI / 2, false);
 ctx.stroke();
 
 var imageData = ctx.getImageData(0, 0, 1, 1);
 var imgdata = imageData.data;
 shouldBe("imgdata[0]", "0");
 shouldBe("imgdata[1]", "255");
 shouldBe("imgdata[2]", "0");
 
 imageData = ctx.getImageData(125, 30, 1, 1);
 imgdata = imageData.data;
 shouldBe("imgdata[0]", "0");
 shouldBe("imgdata[1]", "255");
 shouldBe("imgdata[2]", "0");
 
 imageData = ctx.getImageData(125, 70, 1, 1);
 imgdata = imageData.data;
 shouldBe("imgdata[0]", "0");
 shouldBe("imgdata[1]", "0");
 shouldBe("imgdata[2]", "0");