message: Convert `MainWeb.startUp()` to async/await
diff: @@ -76,7 +76,7 @@ let commandPalette: CommandPalette = null;
  let applicationContextMenu: ApplicationContextMenu = null;
  -export function startUp(closeSplash: () => void): void {
  +export async function startUp(closeSplash: () => void): Promise<void> {
  ElectronMenu.setApplicationMenu(null);
  startUpTheming();
  @@ -85,13 +85,14 @@ export function startUp(closeSplash: () => void): void {
  // Get the Config working.
  configDatabase = new ConfigDatabaseImpl();
  keybindingsManager = new KeybindingsManagerImpl(); // depends on the config.
  - const configPromise = WebIpc.requestConfig("*").then( (msg: Messages.ConfigMessage) => {
  - return handleConfigMessage(msg);
  - });
  - // Get the config and theme info in and then continue starting up.
  - const allPromise = Promise.all<void>( [configPromise, WebIpc.requestThemeList().then(handleThemeListMessage)] );
  - allPromise.then(loadFontFaces).then( () => {
  + const configMsg = await WebIpc.requestConfig("*");
  + handleConfigMessage(configMsg);
  +
  + const themeListMsg = await WebIpc.requestThemeList()
  + handleThemeListMessage(themeListMsg);
  +
  + await loadFontFaces();
  const doc = window.document;
  doc.body.classList.add(CLASS_MAIN_NOT_DRAGGING);
  @@ -118,7 +119,6 @@ export function startUp(closeSplash: () => void): void {
  }
  mainWebUi.focus();
  window.focus();
  - });
  }
  function startUpTheming(): void {
  