* 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.cc
#if defined(OS_MACOSX)
  if (!draggable_regions_.empty())
    UpdateDraggableRegions(nullptr, draggable_regions_);
#endif
  TopLevelWindow::OnWindowResize();
}
void BrowserWindow::OnWindowLeaveFullScreen() {
  TopLevelWindow::OnWindowLeaveFullScreen();
#if defined(OS_MACOSX)
  if (web_contents()->IsFullscreenForCurrentTab())
    web_contents()->ExitFullscreen(true);
#endif
}
void BrowserWindow::Focus() {
  if (api_web_contents_->IsOffScreen())
    FocusOnWebView();
  else
    TopLevelWindow::Focus();
}
void BrowserWindow::Blur() {
  if (api_web_contents_->IsOffScreen())
    BlurWebView();
  else
    TopLevelWindow::Blur();
}
void BrowserWindow::SetBackgroundColor(const std::string& color_name) {