* Electron version: 1.7.9
* Operating system: macOS 10.13.1

### Expected behavior

If pinch-zoom is disabled via `webFrame.setVisualZoomLevelLimits(1, 1);` it should stay disabled.

### Actual behavior

Pinch zoom is possible. 

### How to reproduce

* connect an external monitor and open any electron app there, keep the macbook pro lid closed
* disconnect the external monitor
* open the lid

=> you can now pinch zoom 
atom/renderer/api/atom_api_web_frame.cc
blink::WebFrame* frame = web_frame_->NextSibling();
  if (frame && frame->IsWebLocalFrame())
    return mate::CreateHandle(isolate(),
                              new WebFrame(isolate(),
                                           frame->ToWebLocalFrame())).ToV8();
  else
    return v8::Null(isolate());
}
v8::Local<v8::Value> WebFrame::GetFrameForSelector(
    const std::string& selector) const {
  blink::WebElement element = web_frame_->GetDocument().QuerySelector(
      blink::WebString::FromUTF8(selector));
  blink::WebLocalFrame* element_frame =
      blink::WebLocalFrame::FromFrameOwnerElement(element);
  if (element_frame)
    return mate::CreateHandle(isolate(),
                              new WebFrame(isolate(), element_frame)).ToV8();
  else
    return v8::Null(isolate());
}
v8::Local<v8::Value> WebFrame::FindFrameByName(const std::string& name) const {
  blink::WebLocalFrame* local_frame = web_frame_->FindFrameByName(
      blink::WebString::FromUTF8(name))->ToWebLocalFrame();
  if (local_frame)
    return mate::CreateHandle(isolate(),
                              new WebFrame(isolate(), local_frame)).ToV8();
  else
    return v8::Null(isolate());
}
void WebFrame::BuildPrototype(