Add support for new canvas ellipse method.

LayoutTests/fast/canvas/script-tests/canvas-ellipse-360-winding.js

 description("This tests canvas full arc fill with nonzero winding rule. Eight green concentric thick circumferences should be displayed.");
 
 var canvas = document.createElement('canvas');
 document.body.appendChild(canvas)
 canvas.setAttribute('width', '300');
 canvas.setAttribute('height', '150');
 var ctx = canvas.getContext('2d');
 
 var r;
 var anticlockwise = true;
 ctx.beginPath();
 for (r = 200; r >= 10; r -= 10) {
     ctx.moveTo(150 + r, 75);
-    ctx.arc(150, 75, r, 0, Math.PI*2, anticlockwise);
+    ctx.ellipse(150, 75, r, r * 1.2, 0, 0, Math.PI * 2, anticlockwise);
     ctx.closePath();
     anticlockwise = !anticlockwise;
 }
 ctx.fillStyle = 'rgba(0, 255, 0, 1)';
 ctx.strokeStyle = 'rgba(0, 255, 0, 1)';
 ctx.fill();
 ctx.stroke();
 
 var imageData = ctx.getImageData(297, 75, 1, 1);
 var data = imageData.data;
-shouldBe("data[0]", "0");
 shouldBe("data[1]", "0");
-shouldBe("data[2]", "0");
 
-imageData = ctx.getImageData(285, 5, 1, 1);
+imageData = ctx.getImageData(295, 144, 1, 1);
 data = imageData.data;
-shouldBe("data[0]", "0");
 shouldBe("data[1]", "255");
-shouldBe("data[2]", "0");
 
-imageData = ctx.getImageData(277, 75, 1, 1);
+imageData = ctx.getImageData(272, 144, 1, 1);
 data = imageData.data;
-shouldBe("data[0]", "0");
+shouldBe("data[1]", "255");
+
+imageData = ctx.getImageData(262, 144, 1, 1);
+data = imageData.data;
 shouldBe("data[1]", "0");
-shouldBe("data[2]", "0");
+
+imageData = ctx.getImageData(239, 144, 1, 1);
+data = imageData.data;
+shouldBe("data[1]", "0");
+
+imageData = ctx.getImageData(228, 144, 1, 1);
+data = imageData.data;
+shouldBe("data[1]", "255");