Bug 1616407 - Add crash test for fuzzer test case r=emilio

Differential Revision: https://phabricator.services.mozilla.com/D64613

--HG--
extra : moz-landing-system : lando

layout/style/crashtests/1616407.html

@@ -0,0 +1,7 @@
+<script>
+    async function start() {
+      var a = new CSSStyleSheet({ })
+      document.adoptedStyleSheets = [new CSSStyleSheet({ }), a, a]
+    }
+    document.addEventListener('DOMContentLoaded', start)
+  </script>

layout/style/crashtests/crashtests.list

@@ -317,3 +317,4 @@ load 1586444.html
 load 1599286.html
 pref(layout.css.motion-path.enabled,true) load 1609786.html
 pref(layout.css.constructable-stylesheets.enabled,true) load 1616433.html
+pref(layout.css.constructable-stylesheets.enabled,true) load 1616407.html