* **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
#if defined(OS_WIN)
  DWORD affinity = enable ? WDA_MONITOR : WDA_NONE;
  ::SetWindowDisplayAffinity(GetAcceleratedWidget(), affinity);
#endif
}
void NativeWindowViews::SetFocusable(bool focusable) {
#if defined(OS_WIN)
  LONG ex_style = ::GetWindowLong(GetAcceleratedWidget(), GWL_EXSTYLE);
  if (focusable)
    ex_style &= ~WS_EX_NOACTIVATE;
  else
    ex_style |= WS_EX_NOACTIVATE;
  ::SetWindowLong(GetAcceleratedWidget(), GWL_EXSTYLE, ex_style);
  SetSkipTaskbar(!focusable);
  Focus(false);
#endif
}
void NativeWindowViews::SetMenu(AtomMenuModel* menu_model) {
#if defined(USE_X11)
  if (menu_model == nullptr) {
    global_menu_bar_.reset();
    root_view_->UnregisterAcceleratorsWithFocusManager();
    return;
  }
  if (!global_menu_bar_ && ShouldUseGlobalMenuBar())
    global_menu_bar_.reset(new GlobalMenuBarX11(this));
  
  if (global_menu_bar_ && global_menu_bar_->IsServerStarted()) {
    root_view_->RegisterAcceleratorsWithFocusManager(menu_model);