message: Clear sessionStorage on sign out
  The browser's `sessionStorage` is only used for composer history today, but
  still we should also clear this on sign out for those on shared computers, etc.
  Fixes
diff: @@ -637,6 +637,10 @@ async function _clearStorage() {
  window.localStorage.clear();
  }
  + if (window.sessionStorage) {
  + window.sessionStorage.clear();
  + }
  +
  // create a temporary client to clear out the persistent stores.
  const cli = createMatrixClient({
  // we'll never make any requests, so can pass a bogus HS URL
  