Bug 1539947 - Disable browser_thumbnails_update.js on windows qr for frequent failures. r=gbrown

Differential Revision: https://phabricator.services.mozilla.com/D49386

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

toolkit/components/thumbnails/test/browser.ini

@@ -44,3 +44,4 @@ skip-if = true # bug 1314039 # Bug 1345418
 [browser_thumbnails_storage.js]
 [browser_thumbnails_storage_migrate3.js]
 [browser_thumbnails_update.js]
+skip-if = (webrender && os == 'win') #Bug 1539947