WhatsApp: Disable initial service workers.

This works around #72 in combination with 3cc306e.

Inspired by ramboxapp/community-edition@9c0f13d, but written from
scratch using Promises to avoid blocking pointlessly while Promises
resolve.

Fixes #72.

app/store/ServicesList.js

@@ -28,7 +28,7 @@ Ext.define('Rambox.store.ServicesList', {
 			,description: locale['services[0]']
 			,url: 'https://web.whatsapp.com/'
 			,type: 'messaging'
-			,js_unread: `let checkUnread=()=>{const elements=document.querySelectorAll(".CxUIE, .unread");let count=0;for(let i of elements)0===i.querySelectorAll('*[data-icon="muted"]').length&&count++;rambox.updateBadge(count)};setInterval(checkUnread,1e3);`
+			,js_unread: `let checkUnread=()=>{const elements=document.querySelectorAll(".CxUIE, .unread");let count=0;for(let i of elements)0===i.querySelectorAll('*[data-icon="muted"]').length&&count++;rambox.updateBadge(count)};setInterval(checkUnread,1e3);let unregister_queue=[];navigator.serviceWorker.getRegistrations().then(registrations=>{for(const registration of registrations)unregister_queue.push(registration.unregister());return unregister_queue}).then(queue=>{}).catch(err=>{});`
 			,userAgent: 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.181 Safari/537.36'
 			,slowed_timers: false
 		},