Incorrect documentation for fixing memory leaks

The "isMounted is an Antipattern" documentation article suggest avoiding memory leaks with makeCancelable, but this doesn't actually solve the issue since the callback is still referenced. The garbage collector does not understand that setting hasCanceled_ means that resolve will never be called, so it cannot release resolve or the references contained within. Even if it could, reject might also reference this, so memory leaks could still exist. Instead, makeCancelable should store the resolve and reject callbacks itself, and it should null them out on cancelation.

Another user pointed this issue out in https://github.com/facebook/react/issues/5465#issuecomment-287113777

受影響的資料是 issue 中連結的「isMounted is an Antipattern」文章；先檢視其中的 makeCancelable 範例以及所參照的討論。更新文件，讓其中關於記憶體洩漏的指引在技術上正確，然後確認該文章不再建議有爭議的實作。