Apply further ES6 bikeshedding

lib/browser/guest-window-manager.js

@@ -52,10 +52,7 @@ const mergeBrowserWindowOptions = function (embedder, options) {
     // if parent's visibility is available, that overrides 'show' flag (#12125)
     const win = BrowserWindow.fromWebContents(embedder.webContents)
     if (win != null) {
-      const show = win.isVisible()
-      if (typeof show === 'boolean') {
-        parentOptions = {...embedder.browserWindowOptions, show}
-      }
+      parentOptions = {...embedder.browserWindowOptions, show: win.isVisible()}
     }
 
     // Inherit the original options if it is a BrowserWindow.

spec/chromium-spec.js

@@ -223,9 +223,9 @@ describe('chromium feature', () => {
       b = window.open(`file://${fixtures}/pages/window-open-size.html`, '', 'show=no')
     })
 
-    for (const show in [true, false]) {
+    for (const show of [true, false]) {
       it(`inherits parent visibility over parent {show=${show}} option`, (done) => {
-        let w = new BrowserWindow({show: show})
+        const w = new BrowserWindow({show})
 
         // toggle visibility
         if (show) {