Unset stop propagation flags after dispatch

Fixes #219.

dom.bs

@@ -1271,7 +1271,8 @@ for discussion).
    <b>item</b> with <var>event</var>.
   </ol>
 
- <li><p>Unset <var>event</var>'s <a>dispatch flag</a>.
+ <li><p>Unset <var>event</var>'s <a>dispatch flag</a>, <a>stop propagation flag</a>, and
+ <a>stop immediate propagation flag</a>.
 
  <li><p>Set <var>event</var>'s {{Event/eventPhase}} attribute to {{Event/NONE}}.
 

dom.html

@@ -928,7 +928,7 @@ <h3 class="heading settled" data-level="3.8" id="dispatching-events"><span class
        <p>If either <var>event</var>’s <code class="idl"><a data-link-type="idl" href="#dom-event-eventphase">eventPhase</a></code> attribute is <code class="idl"><a data-link-type="idl" href="#dom-event-bubbling_phase">BUBBLING_PHASE</a></code> and <var>event</var>’s <code class="idl"><a data-link-type="idl" href="#dom-event-bubbles">bubbles</a></code> attribute is true or <var>event</var>’s <code class="idl"><a data-link-type="idl" href="#dom-event-eventphase">eventPhase</a></code> attribute is <code class="idl"><a data-link-type="idl" href="#dom-event-at_target">AT_TARGET</a></code>, then <a data-link-type="dfn" href="#concept-event-listener-invoke">invoke</a> <var>tuple</var>’s <b>item</b> with <var>event</var>. </p>
      </ol>
     <li>
-     <p>Unset <var>event</var>’s <a data-link-type="dfn" href="#dispatch-flag">dispatch flag</a>. </p>
+     <p>Unset <var>event</var>’s <a data-link-type="dfn" href="#dispatch-flag">dispatch flag</a>, <a data-link-type="dfn" href="#stop-propagation-flag">stop propagation flag</a>, and <a data-link-type="dfn" href="#stop-immediate-propagation-flag">stop immediate propagation flag</a>. </p>
     <li>
      <p>Set <var>event</var>’s <code class="idl"><a data-link-type="idl" href="#dom-event-eventphase">eventPhase</a></code> attribute to <code class="idl"><a data-link-type="idl" href="#dom-event-none">NONE</a></code>. </p>
     <li>