I was doing two-binding in GWT about 10 years ago (around 2006) when internet explorer 6 was still tormenting developers, but it was laggy in some browsers. Google later released the UI binder "framework" on top of GWT which explicitly called it UI binding which was a form of two-way binding as well. Otherwise JavaScript was just too slow and error prone to have it everywhere before 2005 - Internet explorer would crash if you did too many interactions with the DOM, so most websites were just using javascript for simple form validations otherwise doing full-page form POSTs and reloads. Single page apps were initially discussed around 2003 and US Patent 8136109 was awarded (can someone include the patent here, I'm on mobile).
So two-way binding must have been created after single page apps were invented and before GWT which had it as a feature, so 2003-2006.
Angular JS was only released in 2010, so no, Angular was not the first to use it.