Changing single-line JSDoc comments to multiline requires unnecessary edits

<!-- Please try to reproduce the issue with `typescript@next`. It may have already been fixed. --> **TypeScript Version:** 3.1.3 <!-- Search terms you tried before logging this (so others can find this issue more easily) --> **Search Terms:** jsdoc multiline **Code** ```ts /** |Foo */ ``` 1. Press <kbd>Enter</kbd> at the | ```ts /** * Foo |*/ ``` 2. Press <kbd>Enter</kbd> at the | **Expected behavior:** ```ts /** * Foo */ ``` **Actual behavior:** ```ts /** * Foo * */ ``` The leading `* `&nbsp;has to be deleted now. Empty JSDoc-Comments work: ```ts /**| */ ``` Press <kbd>Enter</kbd> at the | ```ts /** * */ ```