Always fire popstate and restore persisted state sync

Closes #1792 by aligning with Gecko. The alternative model involved delaying popstate until after the load event, which is what WebKit and Blink do. But the Gecko model is simpler, more deterministic (since the load event depends on network timing), and has fewer edge cases around multiple consecutive state changes.

source

@@ -90415,9 +90415,8 @@ new PaymentRequest(…); // Allowed to use
    mode</span>.</p></li>
 
    <li><p><span>Traverse the history</span> to the new entry, with <var
-   data-x="traverse-history-hh">historyHandling</var> set to <var>historyHandling</var> and with
-   <var><span>nonBlockingEvents</span></var> set to true. This will <span>scroll to the
-   fragment</span> given in what is now the document's <span
+   data-x="traverse-history-hh">historyHandling</var> set to <var>historyHandling</var>. This will
+   <span>scroll to the fragment</span> given in what is now the document's <span
    data-x="concept-document-url">URL</span>.</p></li>
 
    <li><p><p>Invoke <span>WebDriver BiDi fragment navigated</span> with <var>browsingContext</var>,
@@ -90559,9 +90558,8 @@ new PaymentRequest(&hellip;); // Allowed to use
   <p>To <dfn>traverse the history</dfn> to a <span>session history entry</span> <var>entry</var>,
   with an optional <span>history handling behavior</span> <dfn
   data-x="traverse-history-hh"><var>historyHandling</var></dfn> (default "<code
-  data-x="hh-default">default</code>"), an optional boolean <dfn><var>nonBlockingEvents</var></dfn>
-  (default false), and an optional boolean <dfn><var>explicitHistoryNavigation</var></dfn> (default
-  false):</p>
+  data-x="hh-default">default</code>"), and an optional boolean
+  <dfn><var>explicitHistoryNavigation</var></dfn> (default false):</p>
 
   <p class="note">This algorithm is not just invoked when <span data-x="traverse the history by a
   delta">explicitly going back or forwards in the session history</span> &mdash; it is also invoked
@@ -90773,28 +90771,22 @@ new PaymentRequest(&hellip;); // Allowed to use
 
    <li><p>Set <var>newDocument</var>'s <span>latest entry</span> to <var>entry</var>.</p></li>
 
-   <li>
-    <p>If <var>nonBlockingEvents</var> is false, then run the following steps
-    <span>immediately</span>. Otherwise, <span>queue a global task</span> on the <span>DOM
-    manipulation task source</span> given <var>newDocument</var>'s <span>relevant global
-    object</span> to run the following steps instead.</p>
+   <li><p>If <var>stateChanged</var> is true, then <span data-x="concept-event-fire">fire an
+   event</span> named <code data-x="event-popstate">popstate</code> at <var>newDocument</var>'s
+   <span>relevant global object</span>, using <code>PopStateEvent</code>, with the <code
+   data-x="dom-PopStateEvent-state">state</code> attribute initialized to
+   <var>state</var>.</p></li>
 
-    <ol>
-     <li><p>If <var>stateChanged</var> is true, then <span data-x="concept-event-fire">fire an
-     event</span> named <code data-x="event-popstate">popstate</code> at <var>newDocument</var>'s
-     <span>relevant global object</span>, using <code>PopStateEvent</code>, with the <code
-     data-x="dom-PopStateEvent-state">state</code> attribute initialized to <var>state</var>.</p></li>
-
-     <li><p><span>Restore persisted state</span> from <var>entry</var>.</p></li>
-
-     <li><p>If <var>hashChanged</var> is true, then <span data-x="concept-event-fire">fire an
-     event</span> named <code data-x="event-hashchange">hashchange</code> at the <span>browsing
-     context</span>'s <span>active window</span>, using <code>HashChangeEvent</code>, with the <code
-     data-x="dom-HashChangeEvent-oldURL">oldURL</code> attribute initialized to <var>oldURL</var>
-     and the <code data-x="dom-HashChangeEvent-newURL">newURL</code> attribute initialized to
-     <var>newURL</var>.</p></li>
-    </ol>
-   </li>
+   <li><p><span>Restore persisted state</span> from <var>entry</var>.</p></li>
+
+   <li><p>If <var>hashChanged</var> is true, then <span>queue a global task</span> on the <span>DOM
+   manipulation task source</span> given <var>newDocument</var>'s <span>relevant global
+   object</span> to <span data-x="concept-event-fire">fire an event</span> named <code
+   data-x="event-hashchange">hashchange</code> at <var>newDocument</var>'s <span>relevant global
+   object</span>, using <code>HashChangeEvent</code>, with the <code
+   data-x="dom-HashChangeEvent-oldURL">oldURL</code> attribute initialized to <var>oldURL</var> and
+   the <code data-x="dom-HashChangeEvent-newURL">newURL</code> attribute initialized to
+   <var>newURL</var>.</p></li>
   </ol>