Fix resetRetrieveHandlers to reset retrieveSourceMap and `retriev…

…eFile` functions

The `handlerExec` function produces functions that are using original `retrieveFileHandlers`/`retrieveMapHandlers` references, so because the array variables are  re-assigned in the `resetRetrieveHandlers` function, `retrieveSourceMap` and `retrieveFile` need to be re-created to point them to correct instances of `retrieveFileHandlers`/`retrieveMapHandlers`.

This fixes:
jestjs/jest#6424
jestjs/jest#7402

source-map-support.js

@@ -557,4 +557,7 @@ exports.resetRetrieveHandlers = function() {
 
   retrieveFileHandlers = originalRetrieveFileHandlers.slice(0);
   retrieveMapHandlers = originalRetrieveMapHandlers.slice(0);
+
+  retrieveSourceMap = handlerExec(retrieveMapHandlers);
+  retrieveFile = handlerExec(retrieveFileHandlers);
 }