Refactors which in TS would generate a type annotation should generate jsdoc in JS

<!-- Please try to reproduce the issue with `typescript@next`. It may have already been fixed. --> **TypeScript Version:** 3.1.0-dev.201xxxxx <!-- Search terms you tried before logging this (so others can find this issue more easily) --> **Search Terms:** **Code** ```ts // In TS function x(): 42 { return /*extract to inner function*/42; } // In JS // @ts-check /** * @returns {42} */ function x() { return /*extract to inner function*/42; } ``` **Expected behavior:** Under `ts-check`, a refactoring should apply appropriate jsdocs to allow js to typecheck after a refactoring if it typechecked before it. **Actual behavior:**  **Playground Link:** <!-- A link to a TypeScript Playground "Share" link which demonstrates this behavior --> **Related Issues:** <!-- Did you find other bugs that looked similar? -->