Bug 982241: make the UI observe weave:service:setup-complete so that it gets updated correctly when re-signing in after an auth error, r=ttaubert

Changes:
 * start observing weave:service:setup-complete to update the UI after all logins (re-auth, initial sign-in)
 * stop observing FxAccountsCommon.ONLOGIN_NOTIFICATION, since the state we depend on to update the UI never changes interestingly as a result of it firing

--HG--
extra : rebase_source : 8632d597557b7a25ebc31dd53ad5680ac5a72583

browser/base/content/browser-fxaccounts.js

@@ -27,7 +27,7 @@ let gFxAccounts = {
       "weave:service:ready",
       "weave:service:sync:start",
       "weave:service:login:error",
-      FxAccountsCommon.ONLOGIN_NOTIFICATION,
+      "weave:service:setup-complete",
       FxAccountsCommon.ONVERIFIED_NOTIFICATION,
       FxAccountsCommon.ONLOGOUT_NOTIFICATION
     ];