GoJS v1.6.21 creating new go.HTMLInfo() constructor

I’m trying to use the custom TextEditor but I get this error when creating a new TextEditor at this line :
var TextEditor = new go.HTMLInfo();
Uncaught TypeError: go.HTMLInfo is not a constructor
I used the same code as here : http://gojs.net/latest/extensions/TextEditor.js

HTMLInfo is a new feature in v1.7.

Thank you, I’m updating my version then.