Implement ImageData constructors.

LayoutTests/fast/canvas/script-tests/canvas-ImageData.js

+description("Test ImageData constructor");
+
+shouldBeDefined("ImageData");
+shouldBe("ImageData.length", "2");
+
+imageData = new ImageData(100, 50);
+
+shouldBeNonNull("imageData");
+shouldBeNonNull("imageData.data");
+shouldBe("imageData.data[11]", "0");

[Justin Novosad, 2014/03/24 14:21:09]

Why 11? Should check at least one of each RGBA component.

[sof, 2014/03/24 14:57:21]

Good idea; switched to peeking&poking over RGBA values.

+for (i = 0; i < imageData.data.length; ++i) {
+    imageData.data[i] = 231;

[Justin Novosad, 2014/03/24 14:21:09]

Why set everything to 231? You only check element 32 below.

+}
+
+shouldBe("imageData.width", "100");
+shouldBe("imageData.height", "50");
+shouldBe("imageData.data[32]", "231");
+
+shouldThrow("new ImageData(10)");
+shouldThrow("new ImageData(0, 10)");
+shouldThrow("new ImageData(10, 0)");
+shouldThrow("new ImageData('width', 'height')");
+shouldThrow("new ImageData(1 << 31, 1 << 31)");
+
+shouldThrow("new ImageData(new Uint8ClampedArray(0))");
+shouldThrow("new ImageData(new Uint8Array(100), 25)");
+shouldThrow("new ImageData(new Uint8ClampedArray(27), 2)");
+shouldThrow("new ImageData(new Uint8ClampedArray(104), 14)");
+shouldThrow("new ImageData(imageData.data, 0)");
+shouldThrow("new ImageData(imageData.data, 13)");
+shouldThrow("new ImageData(imageData.data, 1 << 31)");
+shouldThrow("new ImageData(imageData.data, 'biggish')");
+shouldThrow("new ImageData(imageData.data, 1 << 24, 1 << 31)");
+
+imageDataFromData = new ImageData(imageData.data, 100);

[Justin Novosad, 2014/03/24 14:00:11]

Would be good to exercise a successful call to this constructor with the
optional height argument.

[sof, 2014/03/24 14:57:21]

Done.

+shouldBe("imageDataFromData.width", "100");
+shouldBe("imageDataFromData.height", "50");
+shouldBe("imageDataFromData.data[34]", "imageData.data[34]");