* Electron Version: v3.0.0-beta.2
* Operating System (Platform and Version): macOS 10.13.5
* Last known working Electron version: v3.0.0-beta.1

**Expected Behavior**
Launching DevTools

**Actual behavior**
Electron crash with current dump:
```
Crashing on exception: *** -[__NSArrayM objectAtIndex:]: index 1 beyond bounds [0 .. 0]

Application Specific Backtrace 1:
0   CoreFoundation                      0x00007fff489d332b __exceptionPreprocess + 171
1   libobjc.A.dylib                     0x00007fff6fb41c76 objc_exception_throw + 48
2   CoreFoundation                      0x00007fff48a14634 _CFThrowFormattedException + 202
3   CoreFoundation                      0x00007fff488f2290 __CFStringDecodeByteStream3 + 0
4   Electron Framework                  0x000000010e7554c2 _ZN9brightray8IOThread7CleanUpEv + 2210
...
```

**Additional info** 
`BrowserWindow` should contain `titleBarStyle` with `hiddenInset` value.

Full dump attached to [link](https://github.com/electron/electron/files/2185677/dump.txt)

atom/browser/api/atom_api_browser_window.h
void RenderViewCreated(content::RenderViewHost* render_view_host) override;
  void DidFirstVisuallyNonEmptyPaint() override;
  void BeforeUnloadDialogCancelled() override;
  void OnRendererUnresponsive(content::RenderProcessHost*) override;
  bool OnMessageReceived(const IPC::Message& message,
                         content::RenderFrameHost* rfh) override;
  
  void OnCloseContents() override;
  void OnRendererResponsive() override;
  
  void RequestPreferredWidth(int* width) override;
  void OnCloseButtonClicked(bool* prevent_default) override;
  
  void OnWindowClosed() override;
  void OnWindowBlur() override;
  void OnWindowFocus() override;
  void OnWindowResize() override;
  void OnWindowLeaveFullScreen() override;
  void Focus() override;
  void Blur() override;
  void SetBackgroundColor(const std::string& color_name) override;
  void SetBrowserView(v8::Local<v8::Value> value) override;
  void SetVibrancy(mate::Arguments* args) override;
  
  void FocusOnWebView();
  void BlurWebView();
  bool IsWebViewFocused();
  v8::Local<v8::Value> GetWebContents(v8::Isolate* isolate);
 private:
#if defined(OS_MACOSX)