* 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
#include "third_party/WebKit/public/web/WebView.h"
#include "third_party/WebKit/Source/platform/weborigin/SchemeRegistry.h"
#include "atom/common/node_includes.h"
namespace mate {
template <>
struct Converter<blink::WebLocalFrame::ScriptExecutionType> {
  static bool FromV8(v8::Isolate* isolate,
                     v8::Local<v8::Value> val,
                     blink::WebLocalFrame::ScriptExecutionType* out) {
    std::string execution_type;
    if (!ConvertFromV8(isolate, val, &execution_type))
      return false;
    if (execution_type == "asynchronous") {
      *out = blink::WebLocalFrame::kAsynchronous;
    } else if (execution_type ==
                   "asynchronousBlockingOnload") {
      *out = blink::WebLocalFrame::kAsynchronousBlockingOnload;
    } else if (execution_type == "synchronous") {
      *out = blink::WebLocalFrame::kSynchronous;
    } else {
      return false;
    }
    return true;
  }
};
}  
namespace atom {
namespace api {
namespace {
class ScriptExecutionCallback : public blink::WebScriptExecutionCallback {