* 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
if (delegate_)
    delegate_->DevToolsStopIndexing(request_id);
}
void InspectableWebContentsImpl::SearchInPath(
    int request_id,
    const std::string& file_system_path,
    const std::string& query) {
  if (delegate_)
    delegate_->DevToolsSearchInPath(request_id, file_system_path, query);
}
void InspectableWebContentsImpl::SetWhitelistedShortcuts(
    const std::string& message) {}
void InspectableWebContentsImpl::SetEyeDropperActive(bool active) {}
void InspectableWebContentsImpl::ShowCertificateViewer(
    const std::string& cert_chain) {}
void InspectableWebContentsImpl::ZoomIn() {
  double new_level = GetNextZoomLevel(GetDevToolsZoomLevel(), false);
  SetZoomLevelForWebContents(GetDevToolsWebContents(), new_level);
  UpdateDevToolsZoomLevel(new_level);
}
void InspectableWebContentsImpl::ZoomOut() {
  double new_level = GetNextZoomLevel(GetDevToolsZoomLevel(), true);
  SetZoomLevelForWebContents(GetDevToolsWebContents(), new_level);
  UpdateDevToolsZoomLevel(new_level);
}
void InspectableWebContentsImpl::ResetZoom() {
  SetZoomLevelForWebContents(GetDevToolsWebContents(), 0.);
  UpdateDevToolsZoomLevel(0.);
}
void InspectableWebContentsImpl::SetDevicesDiscoveryConfig(