Switch userbar icon to SVG

wagtail/admin/static_src/wagtailadmin/scss/userbar.scss

@@ -101,6 +101,10 @@ $positions: (
     border: 0;
     width: auto;
     height: auto;
+
+    &-icon {
+        @include svg-icon(2.5em);
+    }
 }
 
 

wagtail/admin/templates/wagtailadmin/userbar/base.html

@@ -6,7 +6,14 @@
         <div class="wagtail-userbar-nav">
             <div class="wagtail-userbar-trigger" data-wagtail-userbar-trigger>
                 {% block branding_logo %}
-                <i class="wagtail-icon wagtail-icon-wagtail"></i>
+                  <div style="display: none">
+                    <svg>
+                        <defs>
+                          {% include "wagtailadmin/icons/wagtail.svg" %}
+                        </defs>
+                    </svg>
+                  </div>
+                  {% icon name="wagtail-icon" class_name="wagtail-userbar-icon" %}
                 {% endblock %}
                 <span class="wagtail-userbar-help-text">{% trans 'Go to Wagtail admin interface' %}</span>
             </div>