Hello,

First of all Thanks for the awesome work on electron, while trying to upgrade our app, we found webview is crashing, upon digging our logging mechanism which logs all object properties going into prototype chain was causing webview to crash.  we have given minimal code to reproduce the effect.

0.37.x appends a <empty-string> key with each ipc message. when we encounter that key webview crashes.

Sample app can be found in the below git url, working fine in < 0.37.x

```
https://github.com/kamesh-a/electron-samples/tree/master/0.37.2_webview_crash
```
- Electron version: 0.37.x
- Operating system: Mac and Windows

atom/renderer/atom_render_view_observer.cc
#include "atom/renderer/atom_render_view_observer.h"
#include <string>
#include <vector>
#include "atom/common/native_mate_converters/string16_converter.h"
#include "atom/common/api/api_messages.h"
#include "atom/common/api/event_emitter_caller.h"
#include "atom/common/native_mate_converters/value_converter.h"
#include "atom/common/node_includes.h"
#include "atom/common/options_switches.h"
#include "atom/renderer/atom_renderer_client.h"
#include "base/command_line.h"
#include "base/strings/string_number_conversions.h"
#include "content/public/renderer/render_view.h"
#include "ipc/ipc_message_macros.h"
#include "net/base/net_module.h"
#include "net/grit/net_resources.h"
#include "third_party/WebKit/public/web/WebDraggableRegion.h"
#include "third_party/WebKit/public/web/WebDocument.h"
#include "third_party/WebKit/public/web/WebFrame.h"
#include "third_party/WebKit/public/web/WebLocalFrame.h"
#include "third_party/WebKit/public/web/WebKit.h"
#include "third_party/WebKit/public/web/WebView.h"
#include "ui/base/resource/resource_bundle.h"
#include "native_mate/dictionary.h"
namespace atom {
namespace {
bool GetIPCObject(v8::Isolate* isolate,