[auth0-js] Add optional usePostMessage for checkSession, fix travis-ci build error

types/auth0-js/auth0-js-tests.ts

@@ -182,7 +182,14 @@ webAuth.checkSession({
     // Authentication tokens or error
 });
 
-
+webAuth.checkSession({
+  audience: 'https://mystore.com/api/v2',
+  scope: 'read:order write:order',
+  redirectUri: 'https://example.com/auth/silent-callback',
+  usePostMessage: true
+  }, (err, authResult) => {
+    // Renewed tokens or error
+});
 
 const authentication = new auth0.Authentication({
     domain: 'me.auth0.com',

types/auth0-js/index.d.ts

@@ -275,7 +275,7 @@ export class WebAuth {
      * @param options options used in {@link authorize} call
      * @param callback: any(err, token_payload)
      */
-    checkSession(options: AuthorizeOptions, callback: Auth0Callback<any>): void;
+    checkSession(options: CheckSessionOptions, callback: Auth0Callback<any>): void;
 }
 
 export class Redirect {
@@ -761,3 +761,10 @@ export interface AuthorizeOptions {
     scope?: string;
     audience?: string;
 }
+
+export interface CheckSessionOptions extends AuthorizeOptions {
+	/**
+	 * optional parameter for auth0 to use postMessage to communicate between the silent callback and the SPA.
+	 */
+	usePostMessage?: boolean;
+}