* **Electron Version:**
  4.0.2
* **Operating System:**
  macOS 10.14.3
* **Last Known Working Electron version:**:
  1.7

### Expected Behavior
When creating a BrowserWindow it should not appear in the dock menu by defaults.

### Actual Behavior
It appears in the dock menu (example: `raven` in https://electronjs.org/docs/tutorial/macos-dock)

### To Reproduce
Just create new BrowserWindow, then right click on the app icon in the dock. (see https://electronjs.org/docs/tutorial/macos-dock)

At least it should be a way to control that, this can be achieve for top level window with:
`[window_ setExcludedFromWindowsMenu:YES];`, indeed [window isExcludedFromWindowsMenu] returns false by default, see

https://developer.apple.com/documentation/appkit/nsapplication/1428625-removewindowsitem
`Use the isExcludedFromWindowsMenu method of NSWindow if you want the item to remain excluded from the Window menu.`
https://developer.apple.com/documentation/appkit/nswindow/1419175-isexcludedfromwindowsmenu

atom/browser/native_window.h
virtual void SetTitle(const std::string& title) = 0;
  virtual std::string GetTitle() = 0;
  virtual void FlashFrame(bool flash) = 0;
  virtual void SetSkipTaskbar(bool skip) = 0;
  virtual void SetSimpleFullScreen(bool simple_fullscreen) = 0;
  virtual bool IsSimpleFullScreen() = 0;
  virtual void SetKiosk(bool kiosk) = 0;
  virtual bool IsKiosk() = 0;
  virtual void SetBackgroundColor(SkColor color) = 0;
  virtual void SetHasShadow(bool has_shadow) = 0;
  virtual bool HasShadow() = 0;
  virtual void SetOpacity(const double opacity) = 0;
  virtual double GetOpacity() = 0;
  virtual void SetRepresentedFilename(const std::string& filename);
  virtual std::string GetRepresentedFilename();
  virtual void SetDocumentEdited(bool edited);
  virtual bool IsDocumentEdited();
  virtual void SetIgnoreMouseEvents(bool ignore, bool forward) = 0;
  virtual void SetContentProtection(bool enable) = 0;
  virtual void SetFocusable(bool focusable);
  virtual void SetMenu(AtomMenuModel* menu);
  virtual void SetParentWindow(NativeWindow* parent);
  virtual void AddBrowserView(NativeBrowserView* browser_view) = 0;
  virtual void RemoveBrowserView(NativeBrowserView* browser_view) = 0;
  virtual gfx::NativeView GetNativeView() const = 0;
  virtual gfx::NativeWindow GetNativeWindow() const = 0;
  virtual gfx::AcceleratedWidget GetAcceleratedWidget() const = 0;
  virtual NativeWindowHandle GetNativeWindowHandle() const = 0;
  
  enum ProgressState {