* 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
frontend_loaded_ = false;
  external_devtools_web_contents_ = nullptr;
  Observe(nullptr);
  Detach();
  embedder_message_dispatcher_.reset();
  for (const auto& pair : pending_requests_)
    delete pair.first;
  if (view_ && view_->GetDelegate())
    view_->GetDelegate()->DevToolsClosed();
}
bool InspectableWebContentsImpl::DidAddMessageToConsole(
    content::WebContents* source,
    int32_t level,
    const base::string16& message,
    int32_t line_no,
    const base::string16& source_id) {
  logging::LogMessage("CONSOLE", line_no, level).stream()
      << "\"" << message << "\", source: " << source_id << " (" << line_no
      << ")";
  return true;
}
bool InspectableWebContentsImpl::ShouldCreateWebContents(