Fix typos

Author: ip512

src/Google/Auth/OAuth2.php

@@ -192,7 +192,7 @@ public function getAccessToken()
   public function getRefreshToken()
   {
     if (array_key_exists('refresh_token', $this->token)) {
-      return this->token['refresh_token'];
+      return $this->token['refresh_token'];
     } else {
       return null;
     }

src/Google/Client.php

@@ -254,7 +254,7 @@ public function getAccessToken()
    */
   public function getRefreshToken()
   {
-    return = $this->getAuth()->getRefreshToken();
+    return $this->getAuth()->getRefreshToken();
   }
 
   /**