* Output of `node_modules/.bin/electron --version`: v3.0.0-beta.8
* Operating System (Platform and Version): Windows 10 10.0.16299 Build 16299
* Output of `node_modules/.bin/electron --version` on last known working Electron version (if applicable): v2.0.8

**Expected Behavior**
Webview DevTools should open in a window that is properly sized.

**Actual behavior**
Webview DevTools open in window with minimal size and are therefore not visible.

**To Reproduce**
**Edit** Works in BrowserWindow.webContents.openDevTools() Works **not** in webView.openDevTools()

**Screenshots**
![too_small_devtools_window](https://user-images.githubusercontent.com/6893212/44841398-850fed80-ac43-11e8-8bed-849d45473683.png)

**Additional Information**
Only reproducible on Windows 10 10.0.16299 Build 16299. Works correctly on MacOS High Sierra 10.13.4

brightray/browser/inspectable_web_contents_impl.cc
base::WeakPtr<InspectableWebContentsImpl> bindings,
    int stream_id)
    : bindings_(bindings), stream_id_(stream_id) {}
ResponseWriter::~ResponseWriter() {}
int ResponseWriter::Initialize(const net::CompletionCallback& callback) {
  return net::OK;
}
int ResponseWriter::Write(net::IOBuffer* buffer,
                          int num_bytes,
                          const net::CompletionCallback& callback) {
  std::string chunk = std::string(buffer->data(), num_bytes);
  if (!base::IsStringUTF8(chunk))
    return num_bytes;
  base::Value* id = new base::Value(stream_id_);
  base::Value* chunk_value = new base::Value(chunk);
  content::BrowserThread::PostTask(
      content::BrowserThread::UI, FROM_HERE,
      base::BindOnce(&InspectableWebContentsImpl::CallClientFunction, bindings_,
                     "DevToolsAPI.streamWrite", base::Owned(id),
                     base::Owned(chunk_value), nullptr));
  return num_bytes;
}
int ResponseWriter::Finish(int net_error,