test[nodeJS] 047 File flush (async)

"047-11 Flushing data with #fsync:with:"
| fs |
fs := NodeJS fs.
fs open: (TestPath, 'Sample47-11.txt') flags:#w mode:0666 with: [:error :fd| 
   error isNil ifFalse: [self error: '047-11 ' ,error].
   [fs writeSync: fd data: 'Vital Signs' position: 0 ]
	on: Error
	do: [:ex| ^self error: '047-11 ' ,ex].
    fs fsync: fd with:[:err| 
       err isNil ifFalse: [ ^self error: '047-11 ' ,err].
       fs closeSync:fd.
    ]    
].