Update to Drupal 8.0.0-rc3. For more information, see https://www.drupal.org/node/2608078

vendor/jcalderonzumba/gastonjs/src/Browser/BrowserWindowTrait.php

@@ -0,0 +1,81 @@
+<?php
+
+namespace Zumba\GastonJS\Browser;
+
+/**
+ * Class BrowserWindowTrait
+ * @package Zumba\GastonJS\Browser
+ */
+trait BrowserWindowTrait {
+  /**
+   * Returns the current window handle name in the browser
+   * @param string $name
+   * @return mixed
+   */
+  public function windowHandle($name = null) {
+    return $this->command('window_handle', $name);
+  }
+
+  /**
+   * Returns all the window handles present in the browser
+   * @return array
+   */
+  public function windowHandles() {
+    return $this->command('window_handles');
+  }
+
+  /**
+   * Change the browser focus to another window
+   * @param $windowHandleName
+   * @return mixed
+   */
+  public function switchToWindow($windowHandleName) {
+    return $this->command('switch_to_window', $windowHandleName);
+  }
+
+  /**
+   * Opens a new window on the browser
+   * @return mixed
+   */
+  public function openNewWindow() {
+    return $this->command('open_new_window');
+  }
+
+  /**
+   * Closes a window on the browser by a given handler name
+   * @param $windowHandleName
+   * @return mixed
+   */
+  public function closeWindow($windowHandleName) {
+    return $this->command('close_window', $windowHandleName);
+  }
+
+  /**
+   * Gets the current request window name
+   * @return string
+   * @throws \Zumba\GastonJS\Exception\BrowserError
+   * @throws \Exception
+   */
+  public function windowName() {
+    return $this->command('window_name');
+  }
+
+  /**
+   * Zoom factor for a web page
+   * @param $zoomFactor
+   * @return mixed
+   */
+  public function setZoomFactor($zoomFactor) {
+    return $this->command('set_zoom_factor', $zoomFactor);
+  }
+
+  /**
+   * Gets the window size
+   * @param $windowHandleName
+   * @return mixed
+   */
+  public function windowSize($windowHandleName) {
+    return $this->command('window_size', $windowHandleName);
+  }
+
+}