Simplify SyncOnceCell's `take` and `drop`.
Simplify SyncOnceCell's `take` and `drop`.

aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust