Ajust dfn-for of events on XHREventTarget

As discovered in w3c/webref#1216 (comment)

Author: dontcallmedom

Diff for: xhr.bs

@@ -1576,32 +1576,32 @@ steps are:
    <td>The {{XMLHttpRequest/readyState}} attribute changes
    value, except when it changes to <a const for=XMLHttpRequest>UNSENT</a>.
   <tr>
-   <td><dfn id=event-xhr-loadstart event for=XMLHttpRequest><code>loadstart</code></dfn>
+   <td><dfn id=event-xhr-loadstart event for=XMLHttpRequestEventTarget><code>loadstart</code></dfn>
    <td>{{ProgressEvent}}
    <td>The fetch initiates.
   <tr>
-   <td><dfn id=event-xhr-progress event for=XMLHttpRequest><code>progress</code></dfn>
+   <td><dfn id=event-xhr-progress event for=XMLHttpRequestEventTarget><code>progress</code></dfn>
    <td>{{ProgressEvent}}
    <td>Transmitting data.
   <tr>
-   <td><dfn id=event-xhr-abort event for=XMLHttpRequest><code>abort</code></dfn>
+   <td><dfn id=event-xhr-abort event for=XMLHttpRequestEventTarget><code>abort</code></dfn>
    <td>{{ProgressEvent}}
    <td>When the fetch has been aborted. For instance, by invoking the
    {{XMLHttpRequest/abort()}} method.
   <tr>
-   <td><dfn id=event-xhr-error event for=XMLHttpRequest><code>error</code></dfn>
+   <td><dfn id=event-xhr-error event for=XMLHttpRequestEventTarget><code>error</code></dfn>
    <td>{{ProgressEvent}}
    <td>The fetch failed.
   <tr>
-   <td><dfn id=event-xhr-load event for=XMLHttpRequest><code>load</code></dfn>
+   <td><dfn id=event-xhr-load event for=XMLHttpRequestEventTarget><code>load</code></dfn>
    <td>{{ProgressEvent}}
    <td>The fetch succeeded.
   <tr>
-   <td><dfn id=event-xhr-timeout event for=XMLHttpRequest><code>timeout</code></dfn>
+   <td><dfn id=event-xhr-timeout event for=XMLHttpRequestEventTarget><code>timeout</code></dfn>
    <td>{{ProgressEvent}}
    <td>The author specified timeout has passed before the fetch completed.
   <tr>
-   <td><dfn id=event-xhr-loadend event for=XMLHttpRequest><code>loadend</code></dfn>
+   <td><dfn id=event-xhr-loadend event for=XMLHttpRequestEventTarget><code>loadend</code></dfn>
    <td>{{ProgressEvent}}
    <td>The fetch completed (success or failure).
 </table>