lib: simplify function process.emitWarning

PR-URL: #32992
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Andrey Pechkurov <apechkurov@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Juan José Arboleda <soyjuanarbol@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

lib/internal/process/warning.js

@@ -55,7 +55,7 @@ function writeToFile(message) {
 }
 
 function doEmitWarning(warning) {
-  return () => process.emit('warning', warning);
+  process.emit('warning', warning);
 }
 
 let traceWarningHelperShown = false;
@@ -129,7 +129,7 @@ function emitWarning(warning, type, code, ctor) {
     if (process.throwDeprecation)
       throw warning;
   }
-  process.nextTick(doEmitWarning(warning));
+  process.nextTick(doEmitWarning, warning);
 }
 
 function emitWarningSync(warning) {