* 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
.SetMethod("setIsolatedWorldSecurityOrigin",
                 &WebFrame::SetIsolatedWorldSecurityOrigin)
      .SetMethod("setIsolatedWorldContentSecurityPolicy",
                 &WebFrame::SetIsolatedWorldContentSecurityPolicy)
      .SetMethod("setIsolatedWorldHumanReadableName",
                 &WebFrame::SetIsolatedWorldHumanReadableName)
      .SetMethod("getResourceUsage", &WebFrame::GetResourceUsage)
      .SetMethod("clearCache", &WebFrame::ClearCache)
      .SetMethod("getFrameForSelector", &WebFrame::GetFrameForSelector)
      .SetMethod("findFrameByName", &WebFrame::FindFrameByName)
      .SetProperty("opener", &WebFrame::Opener)
      .SetProperty("parent", &WebFrame::Parent)
      .SetProperty("top", &WebFrame::Top)
      .SetProperty("firstChild", &WebFrame::FirstChild)
      .SetProperty("nextSibling", &WebFrame::NextSibling);
}
}  
}  
namespace {
using atom::api::WebFrame;
void Initialize(v8::Local<v8::Object> exports, v8::Local<v8::Value> unused,
                v8::Local<v8::Context> context, void* priv) {
  v8::Isolate* isolate = context->GetIsolate();
  mate::Dictionary dict(isolate, exports);
  dict.Set("webFrame", WebFrame::Create(isolate));
  dict.Set("WebFrame", WebFrame::GetConstructor(isolate)->GetFunction());
}
}  
NODE_BUILTIN_MODULE_CONTEXT_AWARE(atom_renderer_web_frame, Initialize)