* **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_mac.h
void SetVisibleOnAllWorkspaces(bool visible,
                                 bool visibleOnFullScreen) override;
  bool IsVisibleOnAllWorkspaces() override;
  void SetAutoHideCursor(bool auto_hide) override;
  void SelectPreviousTab() override;
  void SelectNextTab() override;
  void MergeAllWindows() override;
  void MoveTabToNewWindow() override;
  void ToggleTabBar() override;
  bool AddTabbedWindow(NativeWindow* window) override;
  bool SetWindowButtonVisibility(bool visible) override;
  void SetVibrancy(const std::string& type) override;
  void SetTouchBar(
      const std::vector<mate::PersistentDictionary>& items) override;
  void RefreshTouchBarItem(const std::string& item_id) override;
  void SetEscapeTouchBarItem(const mate::PersistentDictionary& item) override;
  gfx::Rect ContentBoundsToWindowBounds(const gfx::Rect& bounds) const override;
  gfx::Rect WindowBoundsToContentBounds(const gfx::Rect& bounds) const override;
  
  void OverrideNSWindowContentView();
  
  void SetStyleMask(bool on, NSUInteger flag);
  void SetCollectionBehavior(bool on, NSUInteger flag);
  enum TitleBarStyle {
    NORMAL,
    HIDDEN,
    HIDDEN_INSET,
    CUSTOM_BUTTONS_ON_HOVER,
  };
  TitleBarStyle title_bar_style() const { return title_bar_style_; }