checkJs should imply allowJs

[graingert]

TypeScript Version: 2.3.4

Code

function someJs() {}

Expected behavior:
typechecks ok with --checkJs

Actual behavior:
TS18003: No inputs were found in config file

[graingert]

also setting checkJs true and allowJs false should fail to run

[nickserv]

I agree, I was about to make an issue for this myself. checkJs is invalid without allowJs, and other compilerOptions are implied, so I think it would be more consistent and convenient to imply this as well.

[glen-84]

Fixed in #40275.

[RA80533]

/cc @mhegazy