- 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::WebFloatPoint* out) {
  mate::Dictionary dict;
  if (!ConvertFromV8(isolate, val, &dict))
    return false;
  return dict.Get("x", &out->x) && dict.Get("y", &out->y);
}
bool Converter<blink::WebPoint>::FromV8(
    v8::Isolate* isolate, v8::Local<v8::Value> val, blink::WebPoint* out) {
  mate::Dictionary dict;
  if (!ConvertFromV8(isolate, val, &dict))
    return false;
  return dict.Get("x", &out->x) && dict.Get("y", &out->y);
}
bool Converter<blink::WebSize>::FromV8(
    v8::Isolate* isolate, v8::Local<v8::Value> val, blink::WebSize* out) {
  mate::Dictionary dict;
  if (!ConvertFromV8(isolate, val, &dict))
    return false;
  return dict.Get("width", &out->width) && dict.Get("height", &out->height);
}
bool Converter<blink::WebDeviceEmulationParams>::FromV8(