Make test request using currently active protocol (#388)

For the blob test, make the test request using the active protocol
rather than always using http. At least IE11 will throw an exception
when making an http request from an https domain.

references #387

src/has.ts

@@ -19,7 +19,7 @@ add(
 		}
 
 		const request = new global.XMLHttpRequest();
-		request.open('GET', 'http://www.google.com', true);
+		request.open('GET', global.location.protocol + '//www.google.com', true);
 		request.responseType = 'blob';
 		request.abort();
 		return request.responseType === 'blob';