Allow usage of iterable object in Blob constructor. (#108)

* Allow usage of iterable object in Blob constructor.

* Fix ESLint errors

test.js

@@ -36,6 +36,41 @@ test('Blob ctor parts', async t => {
 	t.is(await blob.text(), 'abcdefg[object Object]foo=');
 });
 
+test('Blob ctor threats an object with @@iterator as a sequence', async t => {
+	const blob = new Blob({[Symbol.iterator]: Array.prototype[Symbol.iterator]});
+
+	t.is(blob.size, 0);
+	t.is(await blob.text(), '');
+});
+
+test('Blob ctor reads blob parts from object with @@iterator', async t => {
+	const input = ['one', 'two', 'three'];
+	const expected = input.join('');
+
+	const blob = new Blob({
+		* [Symbol.iterator]() {
+			yield * input;
+		}
+	});
+
+	t.is(blob.size, new TextEncoder().encode(expected).byteLength);
+	t.is(await blob.text(), expected);
+});
+
+test('Blob ctor threats a string as a sequence', async t => {
+	const expected = 'abc';
+	const blob = new Blob(expected);
+
+	t.is(await blob.text(), expected);
+});
+
+test('Blob ctor threats Uint8Array as a sequence', async t => {
+	const input = [1, 2, 3];
+	const blob = new Blob(new Uint8Array(input));
+
+	t.is(await blob.text(), input.join(''));
+});
+
 test('Blob size', t => {
 	const data = 'a=1';
 	const blob = new Blob([data]);