* Output of `node_modules/.bin/electron --version`: 2.0.0
* Operating System (Platform and Version): Windows 10

**Expected Behavior**
When I disable a window twice via `setEnabled(false)`, I expect the second disable to have no effect.

**Actual behavior**
The second disable is "queued" up, such that I am forced to enable the window twice to get back to normal.

**To Reproduce**
In the electronquickstart repo, in main.js' `createWindow()`, add these lines:

    mainWindow.setEnabled(false);
    mainWindow.setEnabled(false);
    mainWindow.setEnabled(true);

The window will be disabled when launched. 

You see the same issue if you do it in reverse:

    mainWindow.setEnabled(true);
    mainWindow.setEnabled(false); // this doesn't actually disable it, because the window was enabled from the getgo

If this is expected behavior, can the [docs](https://github.com/electron/electron/blob/master/docs/api/browser-window.md#winsetenabledenable) be updated to explain this behavior.
atom/browser/native_window_views.h
void Close() override;
  void CloseImmediately() override;
  void Focus(bool focus) override;
  bool IsFocused() override;
  void Show() override;
  void ShowInactive() override;
  void Hide() override;
  bool IsVisible() override;
  bool IsEnabled() override;
  void SetEnabled(bool enable) override;
  void Maximize() override;
  void Unmaximize() override;
  bool IsMaximized() override;
  void Minimize() override;
  void Restore() override;
  bool IsMinimized() override;
  void SetFullScreen(bool fullscreen) override;
  bool IsFullscreen() const override;
  void SetBounds(const gfx::Rect& bounds, bool animate) override;
  gfx::Rect GetBounds() override;
  gfx::Rect GetContentBounds() override;
  gfx::Size GetContentSize() override;
  gfx::Rect GetNormalBounds() override;
  void SetContentSizeConstraints(
      const extensions::SizeConstraints& size_constraints) override;
  void SetResizable(bool resizable) override;
#if defined(OS_WIN)
  void MoveTop() override;
#endif
  bool IsResizable() override;