* Electron version: 1.7.6
* Operating system: macOS 10.12, Windows 10

### Expected behavior

Right clicking should open context menu in devtools

### Actual behavior

Right clicking does not open the context menu in devtools

### How to reproduce

- `open Electron.app --args --enable-mixed-sandbox`
- open devtools
- right click in the source tab for example
atom/renderer/atom_sandboxed_renderer_client.cc
#include "atom/renderer/atom_sandboxed_renderer_client.h"
#include <string>
#include "atom/common/api/api_messages.h"
#include "atom/common/api/atom_bindings.h"
#include "atom/common/native_mate_converters/string16_converter.h"
#include "atom/common/native_mate_converters/v8_value_converter.h"
#include "atom/common/native_mate_converters/value_converter.h"
#include "atom/common/node_bindings.h"
#include "atom/common/options_switches.h"
#include "atom/renderer/api/atom_api_renderer_ipc.h"
#include "atom/renderer/atom_render_frame_observer.h"
#include "base/command_line.h"
#include "base/files/file_path.h"
#include "chrome/renderer/printing/print_web_view_helper.h"
#include "content/public/renderer/render_frame.h"
#include "native_mate/dictionary.h"
#include "third_party/WebKit/public/web/WebKit.h"
#include "atom/common/node_includes.h"
#include "atom_natives.h"  
namespace atom {
namespace {
const std::string kIpcKey = "ipcNative";
const std::string kModuleCacheKey = "native-module-cache";
v8::Local<v8::Object> GetModuleCache(v8::Isolate* isolate) {