* 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
web_contents()->GetRenderViewHost()->GetWidget()->Focus();
}
void BrowserWindow::BlurWebView() {
  web_contents()->GetRenderViewHost()->GetWidget()->Blur();
}
bool BrowserWindow::IsWebViewFocused() {
  auto* host_view = web_contents()->GetRenderViewHost()->GetWidget()->GetView();
  return host_view && host_view->HasFocus();
}
v8::Local<v8::Value> BrowserWindow::GetWebContents(v8::Isolate* isolate) {
  if (web_contents_.IsEmpty())
    return v8::Null(isolate);
  return v8::Local<v8::Value>::New(isolate, web_contents_);
}
std::unique_ptr<SkRegion> BrowserWindow::DraggableRegionsToSkRegion(
    const std::vector<DraggableRegion>& regions) {
  auto sk_region = std::make_unique<SkRegion>();
  for (const DraggableRegion& region : regions) {
    sk_region->op(
        region.bounds.x(), region.bounds.y(), region.bounds.right(),
        region.bounds.bottom(),
        region.draggable ? SkRegion::kUnion_Op : SkRegion::kDifference_Op);
  }
  return sk_region;
}
void BrowserWindow::ScheduleUnresponsiveEvent(int ms) {