- Electron version: 1.4.0
- Operating system: OS X 10.10.5

I've been using the following code to send Tab key events to a webview in my project:

``` js
const webContents = webView.getWebContents();
const keyEvent = {
  type: 'keyDown',
  keyCode: 'Tab'
};

webContents.sendInputEvent(keyEvent);
```

I have had no issues with this until the recent update to 1.4.0.

The last version the above code works in OS X is **1.3.7**. I've tried this with the latest versions of Electron (1.4.1 & 1.4.2) with the same results.

Am I doing something wrong here? Is this a known issue?

atom/common/native_mate_converters/blink_converter.cc
v8::Isolate* isolate, v8::Local<v8::Value> val,
    blink::WebMouseWheelEvent* out) {
  mate::Dictionary dict;
  if (!ConvertFromV8(isolate, val, &dict))
    return false;
  if (!ConvertFromV8(isolate, val, static_cast<blink::WebMouseEvent*>(out)))
    return false;
  dict.Get("deltaX", &out->deltaX);
  dict.Get("deltaY", &out->deltaY);
  dict.Get("wheelTicksX", &out->wheelTicksX);
  dict.Get("wheelTicksY", &out->wheelTicksY);
  dict.Get("accelerationRatioX", &out->accelerationRatioX);
  dict.Get("accelerationRatioY", &out->accelerationRatioY);
  dict.Get("hasPreciseScrollingDeltas", &out->hasPreciseScrollingDeltas);
#if defined(USE_AURA)
  
  bool can_scroll = true;
  if (dict.Get("canScroll", &can_scroll) && !can_scroll) {
    out->hasPreciseScrollingDeltas = false;
    out->modifiers &= ~blink::WebInputEvent::ControlKey;
  }
#endif
  return true;
}
bool Converter<blink::WebFloatPoint>::FromV8(