* 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::SchemeRegistry::RegisterURLSchemeAsSecure(privileged_scheme);
  }
  if (bypassCSP) {
    blink::SchemeRegistry::RegisterURLSchemeAsBypassingContentSecurityPolicy(
        privileged_scheme);
  }
  if (allowServiceWorkers) {
    blink::SchemeRegistry::RegisterURLSchemeAsAllowingServiceWorkers(
        privileged_scheme);
  }
  if (supportFetchAPI) {
    blink::SchemeRegistry::RegisterURLSchemeAsSupportingFetchAPI(
        privileged_scheme);
  }
  if (corsEnabled) {
    blink::SchemeRegistry::RegisterURLSchemeAsCORSEnabled(privileged_scheme);
  }
}
void WebFrame::InsertText(const std::string& text) {
  web_frame_->FrameWidget()
            ->GetActiveWebInputMethodController()
            ->CommitText(blink::WebString::FromUTF8(text),
                         blink::WebVector<blink::WebImeTextSpan>(),
                         blink::WebRange(),
                         0);
}
void WebFrame::InsertCSS(const std::string& css) {
  web_frame_->GetDocument().InsertStyleSheet(blink::WebString::FromUTF8(css));
}
void WebFrame::ExecuteJavaScript(const base::string16& code,