Issue #3474707 by roderik: Remove special handling of view-mode from CustomElementsNormalizer

src/CustomElementNormalizer.php

@@ -61,7 +61,6 @@ class CustomElementNormalizer implements NormalizerInterface {
       $result['element'] = $result['is'];
       unset($result['is']);
     }
-    unset($result['view-mode']);
 
     // Collect cache metadata. Since the cache metadata object is passed down
     // to slots, custom elements of slots will add their metadata as well.