MDL-83002 theme_boost: tell behat to wait when initialising drawers

theme/boost/amd/src/drawers.js

@@ -812,7 +812,7 @@ const registerListeners = () => {
     document.addEventListener('focusin', preventOverlap);
     document.addEventListener('focusout', preventOverlap);
 
-    window.addEventListener('resize', debounce(closeOnResizeListener, 400));
+    window.addEventListener('resize', debounce(closeOnResizeListener, 400, {pending: true}));
 };
 
 registerListeners();

theme/boost/templates/drawer.mustache

@@ -57,5 +57,8 @@
     </div>
 </div>
 {{#js}}
-require(['theme_boost/drawers']);
+M.util.js_pending('theme_boost/drawers:load');
+require(['theme_boost/drawers'], function() {
+    M.util.js_complete('theme_boost/drawers:load');
+});
 {{/js}}