Use StructuredSerializeForStorage

As defined by and discussed in whatwg/html#2518.

notifications.bs

@@ -190,7 +190,8 @@ these steps:
   <code>TypeError</code> exception.
 
   <li><p>Set <var>notification</var>'s <a for=notification>data</a> to
-  <span>StructuredSerialize</span>(<var>options</var>'s <code>data</code>). Rethrow any exceptions.
+  <a abstract-op>StructuredSerializeForStorage</a>(<var>options</var>'s <code>data</code>). Rethrow
+  any exceptions.
 
   <li><p>Set <var>notification</var>'s <a for=notification>title</a>
   to <var>options</var>'s <code>title</code>.
@@ -895,7 +896,7 @@ the <a>notification</a>'s <a for=notification>renotify preference flag</a>.
 return the <a>notification</a>'s <a for=notification>require interaction preference flag</a>.
 
 <p>The <dfn attribute for=Notification><code>data</code></dfn> attribute's getter must return
-<span>StructuredDeserialize</span>(<a>notification</a>'s <a for=notification>data</a>,
+<a abstract-op>StructuredDeserialize</a>(<a>notification</a>'s <a for=notification>data</a>,
 <a>context object</a>'s <a>relevant Realm</a>). If this throws an exception, then return null.
 <!-- Relies on SameObject becoming Cached as proposed -->