* **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 SelectNextTab();
  virtual void MergeAllWindows();
  virtual void MoveTabToNewWindow();
  virtual void ToggleTabBar();
  virtual bool AddTabbedWindow(NativeWindow* window);
  
  virtual bool SetWindowButtonVisibility(bool visible);
  
  virtual void SetAutoHideMenuBar(bool auto_hide);
  virtual bool IsMenuBarAutoHide();
  virtual void SetMenuBarVisibility(bool visible);
  virtual bool IsMenuBarVisible();
  
  double GetAspectRatio();
  gfx::Size GetAspectRatioExtraSize();
  virtual void SetAspectRatio(double aspect_ratio, const gfx::Size& extra_size);
  
  virtual void PreviewFile(const std::string& path,
                           const std::string& display_name);
  virtual void CloseFilePreview();
  
  virtual gfx::Rect ContentBoundsToWindowBounds(
      const gfx::Rect& bounds) const = 0;
  virtual gfx::Rect WindowBoundsToContentBounds(
      const gfx::Rect& bounds) const = 0;
  base::WeakPtr<NativeWindow> GetWeakPtr() {
    return weak_factory_.GetWeakPtr();
  }
  
  virtual void HandleKeyboardEvent(