Build: Remove unnecessary ESLint exception

The linked-to issue was fixed 2 years ago.

Closes gh-4095

src/core.js

@@ -227,9 +227,6 @@ jQuery.extend( {
 	},
 
 	isEmptyObject: function( obj ) {
-
-		/* eslint-disable no-unused-vars */
-		// See https://github.com/eslint/eslint/issues/6125
 		var name;
 
 		for ( name in obj ) {