Return empty a empty stream for zero sized blob (#86)

Return empty a empty stream for zero sized blob

test.js

@@ -172,6 +172,12 @@ test('Reading from the stream created by blobFrom', async t => {
 	t.is(actual, expected);
 });
 
+test('Reading empty blobs', async t => {
+	const blob = blobFrom('./LICENSE').slice(0, 0);
+	const actual = await blob.text();
+	t.is(actual, '');
+});
+
 test('Blob-ish class is an instance of Blob', t => {
 	class File {
 		stream() {}