Implement addPath() method for Path object

LayoutTests/fast/canvas/script-tests/canvas-path-addpath.js

Index: LayoutTests/fast/canvas/script-tests/canvas-path-addpath.js
diff --git a/LayoutTests/fast/canvas/script-tests/canvas-path-addpath.js b/LayoutTests/fast/canvas/script-tests/canvas-path-addpath.js
new file mode 100644
index 0000000000000000000000000000000000000000..02f7ed0d20bf1d8a68b2a4e74f361da8ecebf7e0
--- /dev/null
+++ b/LayoutTests/fast/canvas/script-tests/canvas-path-addpath.js
@@ -0,0 +1,91 @@
+description("Test addPath() method.");
+var ctx = document.createElement('canvas').getContext('2d');
+
+debug("Test addPath() with transform as identity matrix.")
+ctx.beginPath();
+var p1 = new Path();
+p1.rect(0,0,100,100);
+var p2 = new Path();
+p2.rect(0,100,100,100);
+var m = ctx.currentTransform;
+p1.addPath(p2, m);
+ctx.fillStyle = 'yellow';
+ctx.currentPath = p1;
+ctx.fill();
+var imageData = ctx.getImageData(0, 100, 100, 100);
+var imgdata = imageData.data;
+shouldBe("imgdata[4]", "255");
+shouldBe("imgdata[5]", "255");
+shouldBe("imgdata[6]", "0");
+shouldBe("imgdata[7]", "255");
+debug("");
+
+debug("Test addPath() with transform as translate(100, -100).")
+ctx.beginPath();
+var p3 = new Path();
+p3.rect(0,0,100,100);
+var p4 = new Path();
+p4.rect(0,100,100,100);
+m.a = 1; m.b = 0;
+m.c = 0; m.d = 1;
+m.e = 100; m.f = -100;
+p3.addPath(p4, m);
+ctx.fillStyle = 'yellow';
+ctx.currentPath = p3;
+ctx.fill();
+imageData = ctx.getImageData(100, 0, 100, 100);
+imgdata = imageData.data;
+shouldBe("imgdata[4]", "255");
+shouldBe("imgdata[5]", "255");
+shouldBe("imgdata[6]", "0");
+shouldBe("imgdata[7]", "255");
+debug("");
+
+debug("Test addPath() with non-invertible transform.")
+ctx.beginPath();
+var p5 = new Path();
+p5.rect(0,0,100,100);
+var p6 = new Path();
+p6.rect(100,100,100,100);
+m.a = 0; m.b = 0;
+m.c = 0; m.d = 0;
+m.e = 0; m.f = 0;
+p5.addPath(p6, m);
+ctx.fillStyle = 'yellow';
+ctx.currentPath = p5;
+ctx.fill();
+imageData = ctx.getImageData(100, 100, 100, 100);
+imgdata = imageData.data;
+shouldNotBe("imgdata[4]", "255");
+shouldNotBe("imgdata[5]", "255");
+shouldBe("imgdata[6]", "0");
+shouldNotBe("imgdata[7]", "255");
+debug("");
+
+debug("Test addPath() with transform as null or invalid type.")
+ctx.beginPath();
+var p7 = new Path();
+p7.rect(0,0,100,100);
+var p8 = new Path();
+p8.rect(100,100,100,100);
+p7.addPath(p8, null);
+p7.addPath(p8, []);
+p7.addPath(p8, {});
+ctx.fillStyle = 'red';
+ctx.currentPath = p7;
+ctx.fill();
+imageData = ctx.getImageData(100, 100, 100, 100);
+imgdata = imageData.data;
+shouldBe("imgdata[4]", "255");
+shouldBe("imgdata[5]", "0");
+shouldBe("imgdata[6]", "0");
+shouldBe("imgdata[7]", "255");
+debug("");
+
+debug("Test addPath() with path as null and invalid type");
+var p9 = new Path();
+p9.rect(0,0,100,100);
+shouldThrow("p7.addPath(null, m)");
+shouldThrow("p7.addPath([], m)");
+shouldThrow("p7.addPath({}, m)");
+debug("");