Fix errors in IIIF code

- missing import in IIIFInfo
- syntax errors in IIIF

src/ol/format/IIIFInfo.js

@@ -2,6 +2,8 @@
  * @module ol/format/IIIFInfo
  */
 
+import {assert} from '../asserts.js';
+
 /**
  * Supported image formats, qualities and supported region / size calculation features
  * for different image API versions and compliance levels