* **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_views.cc
frame_style |= WS_MINIMIZEBOX;
    if (maximizable_)
      frame_style |= WS_MAXIMIZEBOX;
    
    if (!thick_frame_)
      frame_style &= ~(WS_THICKFRAME | WS_CAPTION);
    ::SetWindowLong(GetAcceleratedWidget(), GWL_STYLE, frame_style);
  }
  LONG ex_style = ::GetWindowLong(GetAcceleratedWidget(), GWL_EXSTYLE);
  if (window_type == "toolbar")
    ex_style |= WS_EX_TOOLWINDOW;
  ::SetWindowLong(GetAcceleratedWidget(), GWL_EXSTYLE, ex_style);
#endif
  if (has_frame()) {
    
    
    widget()->set_frame_type(views::Widget::FrameType::FRAME_TYPE_FORCE_NATIVE);
    widget()->FrameTypeChanged();
#if defined(OS_WIN)
    
    if (!thick_frame_)
      FlipWindowStyle(GetAcceleratedWidget(), false, WS_THICKFRAME);
#endif
  }
  
  SetContentView(new views::View());
  gfx::Size size = bounds.size();
  if (has_frame() &&
      options.Get(options::kUseContentSize, &use_content_size_) &&
      use_content_size_)