Update externs

Author: sam-gc

packages/firebase/externs/firebase-auth-externs.js

@@ -1218,15 +1218,17 @@ firebase.auth.Auth.prototype.app;
  */
 firebase.auth.Auth.prototype.currentUser;
 
+
 /**
- * The full emulator configuration as set on auth().emulatorConfig
+ * The full emulator configuration as set on `auth().emulatorConfig`.
  * <ul>
  * <li>protocol: the protocol used by the emulator (http or https).</li>
  * <li>host: the host used to reach the emulator.</li>
  * <li>port: the port used to reach the emulator.</li>
  * <li>options: a list of options used to configure the SDK's interaction with
  * the emulator.</li>
  * </ul>
+ *
  * @typedef {{
  *   protocol: string,
  *   host: string,
@@ -1237,26 +1239,29 @@ firebase.auth.Auth.prototype.currentUser;
  * }}
  */
 firebase.auth.EmulatorConfig;
-
+ 
+ 
 /**
- * The current emulator configuration, or null if not set
+ * The current emulator configuration, or null if not set.
  *
  * @type {firebase.auth.EmulatorConfig|null}
  */
 firebase.auth.Auth.prototype.emulatorConfig;
-
+ 
+ 
 /**
- * Configures the SDK to talke to the Firebase Auth emulator.
+ * Configures the SDK to communicate with the Firebase Auth emulator.
  *
  * This must be called before any other Auth SDK actions are taken.
  *
  * Options can include `disableWarnings`. When set to true, the SDK will not
  * display a warning banner at the bottom of the page.
  *
  * @param {string} url The full emulator url including scheme and port.
- * @param {?Object} options Options for configuring the SDK's emulator config.
+ * @param {!Object=} options Options for configuring the SDK's emulator config.
  */
 firebase.auth.Auth.prototype.useEmulator = function (url, options) {};
+ 
 
 /**
  * The current Auth instance's tenant ID. This is a readable/writable