[js] Adjust type annotations to properly track types when generating API docs.

No functional changes.

Author: jleyba

javascript/node/selenium-webdriver/lib/session.js

@@ -27,8 +27,8 @@ class Session {
 
   /**
    * @param {string} id The session ID.
-   * @param {!(Object|Capabilities)} capabilities The session
-   *     capabilities.
+   * @param {!./capabilities.Capabilities} capabilities
+   *     The session capabilities.
    */
   constructor(id, capabilities) {
     /** @private {string} */

javascript/node/selenium-webdriver/lib/webdriver.js

@@ -618,8 +618,8 @@ function filterNonW3CCaps(capabilities) {
  */
 class WebDriver {
   /**
-   * @param {!(Session|IThenable<!Session>)} session Either a known session or a
-   *     promise that will be resolved to a session.
+   * @param {!(./session.Session|IThenable<!./session.Session>)} session Either
+   *     a known session or a promise that will be resolved to a session.
    * @param {!command.Executor} executor The executor to use when sending
    *     commands to the browser.
    * @param {(function(this: void): ?)=} onQuit A function to call, if any,