In fact, it already happened to this proposal, which started life as `Array.prototype.item` before it turned out that some libraries were using the presence of

In fact, it already happened to this proposal, which started life as `Array.prototype.item` before it turned out that some libraries were using the presence of a `.item` property to duck-type DOM collections: https://github.com/tc39/proposal-relative-indexing-method#web-incompatibility-history https://github.com/tc39/proposal-relative-indexing-method#we...