* 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_ = true;
  if (managed_devtools_web_contents_)
    view_->ShowDevTools();
  
  if (!can_dock_) {
    SetIsDocked(DispatchCallback(), false);
  } else {
    if (dock_state_.empty()) {
      const base::DictionaryValue* prefs =
          pref_service_->GetDictionary(kDevToolsPreferences);
      std::string current_dock_state;
      prefs->GetString("currentDockState", &current_dock_state);
      base::RemoveChars(current_dock_state, "\"", &dock_state_);
    }
    base::string16 javascript = base::UTF8ToUTF16(
        "Components.dockController.setDockSide(\"" + dock_state_ + "\");");
    GetDevToolsWebContents()->GetMainFrame()->ExecuteJavaScript(javascript);
  }
  if (view_->GetDelegate())
    view_->GetDelegate()->DevToolsOpened();
}
void InspectableWebContentsImpl::SetInspectedPageBounds(const gfx::Rect& rect) {
  DevToolsContentsResizingStrategy strategy(rect);
  if (contents_resizing_strategy_.Equals(strategy))
    return;
  contents_resizing_strategy_.CopyFrom(strategy);
  if (managed_devtools_web_contents_)
    view_->SetContentsResizingStrategy(contents_resizing_strategy_);
}
void InspectableWebContentsImpl::InspectElementCompleted() {}