If you use Chrome and you have advanced spell check on, you are.
A good practice is to not send ALL your keystrokes off from your browser to a third party like Google. When logging into different web sites, many times you are logging in with passwords. This means your passwords might be leaving your browser and sending them to Google.
Here is how to turn this off.
In Chrome go to Settings->Advanced->Languages. In the Spell Check section make sure “Basic spell check” is selected. That’s it.