Nojs chat form: change default submittable input on Firefox

This reorders the elements so the comment submit input comes before the
captcha image input (that reloads the form). If a non-submittable input
is active and you press enter, Firefox chooses the first submittable
input and submits the form as if that input were clicked. Before this,
pressing enter on the captcha answer input would reload the form instead
of submitting the comment.

anonstream/templates/nojs_form.html

@@ -100,6 +100,11 @@
       background-color: black;
       border-color: #3584e4;
     }
+    #chat-form__exit,
+    #chat-form__captcha-image,
+    #chat-form__captcha-answer {
+      grid-row: 2;
+    }
     #chat-form__captcha-image {
       align-self: center;
       font-size: 8pt;
@@ -204,13 +209,13 @@
   <form id="chat-form" action="{{ url_for('nojs_submit_message', token=user.token) }}" method="post">
     <input type="hidden" name="nonce" value="{{ nonce }}">
     <textarea id="chat-form__comment" name="comment" maxlength="512" {% if digest is none %}required {% endif %} placeholder="Send a message..." rows="1" tabindex="1">{{ state.comment }}</textarea>
+    <input id="chat-form__submit" type="submit" value="Chat" tabindex="4" accesskey="p">
     <div id="chat-form__exit"><a href="#appearance">Settings</a></div>
     {% if digest %}
       <input type="hidden" name="captcha-digest" value="{{ digest }}">
       <input id="chat-form__captcha-image" type="image" formaction="{{ url_for('nojs_form_redirect', token=user.token) }}" formnovalidate src="{{ url_for('captcha', token=user.token, digest=digest) }}" width="72" height="30" alt="Captcha failed to load" title="Click for a new captcha" tabindex="2">
       <input id="chat-form__captcha-answer" name="captcha-answer" required placeholder="Captcha" tabindex="3">
     {% endif %}
-    <input id="chat-form__submit" type="submit" value="Chat" tabindex="4" accesskey="p">
   </form>
   <form id="appearance-form" action="{{ url_for('nojs_submit_appearance', token=user.token) }}" method="post">
     <label id="appearance-form__label-name" for="appearance-form__name">Name:</label>