Editorial: minor editorial fixes to storage broadcast and remove

The remove steps do not return anything, so we do not need to return null. Additionally, the url attribute of StorageEvent is a USVString, so let's initialize the event with the serialization of URL for clarity.

source

@@ -122913,7 +122913,8 @@ interface <dfn interface>Storage</dfn> {
   <ol>
    <li><p>Let <var>thisDocument</var> be <var>storage</var>'s <span>relevant global object</span>'s <span data-x="concept-document-window">associated <code>Document</code></span>.</p></li>
 
-   <li><p>Let <var>url</var> be <var>thisDocument</var>'s <span data-x="concept-document-url">URL</span>.</p></li>
+   <li><p>Let <var>url</var> be the <span data-x="concept-url-serializer">serialization</span> of
+   <var>thisDocument</var>'s <span data-x="concept-document-url">URL</span>.</p></li>
 
    <li>
     <p>Let <var>remoteStorages</var> be all <code>Storage</code> objects excluding
@@ -123032,7 +123033,7 @@ interface <dfn interface>Storage</dfn> {
 
   <ol>
    <li><p>If <span>this</span>'s <span data-x="concept-Storage-map">map</span>[<var>key</var>] does
-   not <span data-x="map exists">exist</span>, then return null.</p></li>
+   not <span data-x="map exists">exist</span>, then return.</p></li>
 
    <li><p>Set <var>oldValue</var> to <span>this</span>'s <span
    data-x="concept-Storage-map">map</span>[<var>key</var>].</p></li>