Google+ Developers Live: Verifying Tokens on Your Server
У вашего броузера проблема в совместимости с HTML5
When, why, and how. Learn to quickly verify ID tokens and access tokens from your client apps for fast, secure authentication on your server.
You can check out related samples on GitHub:
https://github.com/googleplus/gplus-verifytoken-python
https://github.com/googleplus/gplus-verifytoken-php
https://github.com/googleplus/gplus-verifytoken-ruby
https://github.com/googleplus/gplus-verifytoken-csharp
https://github.com/googleplus/gplus-verifytoken-java