ES5 introduce "use strict" and normatively define what language constructions and API usage are deprecated / obsolete.
Links to specs is referenced in https://developer.mozilla.org/en-US/docs/Web/JavaScript/Language_Resources
I tried to read ES6 and make searches for deprecated / obsolete keywords but didn't find anything related.
I compared Annex C of ES6 and ES5 (The Strict Mode of ECMAScript section) and they are mostly identical.
What language constructs or API is deprecated by ECMA 2015 / ES6?