module: remove unnecessary nonInternalExists check

The NativeModule.nonInternalExists(request) is unnecessary in
Module._resolveLookupPaths(), because the check is pre-exist in
Module._resolveFilename()

Author: JacksonTian

lib/module.js

@@ -352,11 +352,6 @@ if (process.platform === 'win32') {
 var indexChars = [ 105, 110, 100, 101, 120, 46 ];
 var indexLen = indexChars.length;
 Module._resolveLookupPaths = function(request, parent, newReturn) {
-  if (NativeModule.nonInternalExists(request)) {
-    debug('looking for %j in []', request);
-    return (newReturn ? null : [request, []]);
-  }
-
   // Check for relative path
   if (request.length < 2 ||
       request.charCodeAt(0) !== 46/*.*/ ||