Align the final (hopefully) constructor with modern IDL

Fixes #5685.

Author: annevk

source

@@ -74652,9 +74652,10 @@ body { display:none }
   <p><code>DataTransfer</code> objects are used to expose the <span>drag data store</span> that
   underlies a drag-and-drop operation.</p>
 
-  <pre><code class="idl" data-x="">[Exposed=Window,
- <span data-x="dom-DataTransfer">Constructor</span>]
+  <pre><code class="idl" data-x="">[Exposed=Window]
 interface <dfn>DataTransfer</dfn> {
+  <span data-x="dom-DataTransfer">constructor</span>();
+
   attribute DOMString <span data-x="dom-DataTransfer-dropEffect">dropEffect</span>;
   attribute DOMString <span data-x="dom-DataTransfer-effectAllowed">effectAllowed</span>;