Docs:
https://github.com/electron/electron/blob/master/docs/api/session.md#sesclearstoragedataoptions-callback

I was running into a strange error when calling the `clearStorageData` method. It was saying it was unable to process the argument at index 1, which I was not passing. After some research I found that the callback is currently required, but in my case I did not care to provide one. To fix it, I supplied an empty function. Here is my code:

```
Electron.remote.getCurrentWebContents().session.clearStorageData(
    {
        storages: [
            'appcache',
            'cookies',
            'filesystem',
            'indexdb',
            'localstorage',
            'shadercache',
            'websql',
            'serviceworkers',
        ],
        quotas: [
            'temporary',
            'persistent',
            'syncable',
        ],
    },
    function() {} // <--- I shouldn't have to do this
);
```
- Electron version: 1.2.7
- Operating system: macOS

atom/browser/api/atom_api_session.cc
v8::Isolate* isolate, AtomBrowserContext* browser_context) {
  auto existing = TrackableObject::FromWrappedClass(isolate, browser_context);
  if (existing)
    return mate::CreateHandle(isolate, static_cast<Session*>(existing));
  auto handle = mate::CreateHandle(
      isolate, new Session(isolate, browser_context));
  g_wrap_session.Run(handle.ToV8());
  return handle;
}
mate::Handle<Session> Session::FromPartition(
    v8::Isolate* isolate, const std::string& partition,
    const base::DictionaryValue& options) {
  scoped_refptr<AtomBrowserContext> browser_context;
  if (partition.empty()) {
    browser_context = AtomBrowserContext::From("", false, options);
  } else if (base::StartsWith(partition, kPersistPrefix,
                              base::CompareCase::SENSITIVE)) {
    std::string name = partition.substr(8);
    browser_context = AtomBrowserContext::From(name, false, options);
  } else {
    browser_context = AtomBrowserContext::From(partition, true, options);
  }
  return CreateFrom(isolate, browser_context.get());
}
void Session::BuildPrototype(v8::Isolate* isolate,