Stripping types should include ts-ignore comments

TypeScript Version: 3.8 latest, playground

Search Terms: remove ts-ignore comment

Code

// this is a comment that should be kept
const message: string = 'hello world';
// the below ts-ignore comment should be removed, since it has no meaning in a non-TS context
// @ts-ignore
console.log(message);

Expected behavior: ts-ignore comment is stripped, other comments are kept.

Actual behavior: all comments are kept including ts-ignore comments.

Playground Link: https://www.typescriptlang.org/play/#code/PTAEBcAsEsGdTqAhqAxgewLaYKYDtwJIlDZJ0BXAGwBNQAjHUAaxwAdwAoDPWQ3WLCQBzHAC5QfAE7Q8w0AF5QAckg4qVdKADu6KbWUBuTiCJNGm7RFgBaaMLx6mGbPlLlqJsAAFwt+45SONzovOhUOAB0msIAFAJCogCUhkA

Related Issues:

[fasttime]

I was actually surprised to find @ts-expect-error comments in my generated .js files. Like @ts-ignore, these are pointless outside TypeScript code.

[rflechtner]

I was actually surprised to find @ts-expect-error comments in my generated .js files. Like @ts-ignore, these are pointless outside TypeScript code.

I was even running into issues where explicitly escaping a type error with @ts-expect-error was compiled to js code where that type error was no longer detected, failing our tests (because the expected error did not occur).