https://lists.w3.org/Archives/Public/public-script-coord/2015JanMar/0033.html
RE: Figuring out the behavior of WindowProxy in the face of non-configurable properties from Travis...
https://developer.mozilla.org/en-US/docs/Glossary/WindowProxy
WindowProxy - Glossary | MDN
A WindowProxy object is a wrapper for a Window object. A WindowProxy object exists in every browsing context. All operations performed on a WindowProxy object...
glossarymdn