Call cleanup Indexed Database transactions

In particular, call it from perform a microtask checkpoint.

Tests: web-platform-tests/wpt#4643.

Fixes #2279.

source

@@ -3191,6 +3191,15 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
 
 
 
+   <dt>Indexed Database API</dt>
+
+   <dd><p>This specification uses <dfn
+   data-x-href="https://w3c.github.io/IndexedDB/#cleanup-indexed-database-transactions">cleanup
+   Indexed Database transactions</dfn> defined by the Indexed Database API specification. <ref
+   spec=INDEXEDDB></p>
+
+
+
    <dt>Media Source Extensions</dt>
 
    <dd>
@@ -88318,6 +88327,8 @@ dictionary <dfn>PromiseRejectionEventInit</dfn> : <span>EventInit</span> {
    event loop</span> is this <span>event loop</span>, <span>notify about rejected promises</span>
    on that <span>environment settings object</span>.</p></li>
 
+   <li><p><span>Cleanup Indexed Database transactions</span>.</p></li>
+
    <li><p>Let the <span>performing a microtask checkpoint</span> flag be false.</p></li>
 
   </ol>
@@ -118734,6 +118745,9 @@ INSERT INTERFACES HERE
    <dt id="refsIANAPERMHEADERS">[IANAPERMHEADERS]</dt>
    <dd><cite><a href="https://www.iana.org/assignments/message-headers/message-headers.xhtml#perm-headers">Permanent Message Header Field Names</a></cite>. IANA.</dd>
 
+   <dt id="refsINDEXEDDB">[INDEXEDDB]</dt>
+   <dd><cite><a href="https://w3c.github.io/IndexedDB/">Indexed Database API</a></cite>, A. Alabbas, J. Bell. W3C.</dd>
+
    <dt id="refsINBAND">[INBAND]</dt>
    <dd><cite><a href="https://dev.w3.org/html5/html-sourcing-inband-tracks/">Sourcing In-band Media Resource Tracks from Media Containers into HTML</a></cite>, S. Pfeiffer, B. Lund. W3C.</dd>