fs: fix immediate WriteStream#end()

Fix an exception that was raised when the WriteStream was closed
immediately after creating it:

  TypeError: Cannot read property 'fd' of undefined
      at WriteStream.close (fs.js:1537:18)
      <snip>

Avoid the TypeError and make sure the file descriptor is closed.

Fixes #4745.

lib/fs.js

@@ -1522,19 +1522,21 @@ ReadStream.prototype.destroy = function() {
 
 
 ReadStream.prototype.close = function(cb) {
+  var self = this;
   if (cb)
     this.once('close', cb);
   if (this.closed || 'number' !== typeof this.fd) {
-    if ('number' !== typeof this.fd)
+    if ('number' !== typeof this.fd) {
       this.once('open', close);
+      return;
+    }
     return process.nextTick(this.emit.bind(this, 'close'));
   }
   this.closed = true;
-  var self = this;
   close();
 
-  function close() {
-    fs.close(self.fd, function(er) {
+  function close(fd) {
+    fs.close(fd || self.fd, function(er) {
       if (er)
         self.emit('error', er);
       else

test/simple/test-fs-write-stream-end.js

@@ -21,27 +21,22 @@
 
 var common = require('../common');
 var assert = require('assert');
+var path = require('path');
+var fs = require('fs');
 
-var path = require('path'),
-    fs = require('fs');
-
-var writeEndOk = false;
 (function() {
-  debugger;
-  var file = path.join(common.tmpDir, 'write-end-test.txt');
+  var file = path.join(common.tmpDir, 'write-end-test0.txt');
   var stream = fs.createWriteStream(file);
-
-  stream.end('a\n', 'utf8');
-  stream.on('close', function() {
-    var content = fs.readFileSync(file, 'utf8');
-    assert.equal(content, 'a\n');
-    writeEndOk = true;
-  });
-
+  stream.end();
+  stream.on('close', common.mustCall(function() { }));
 })();
 
-
-process.on('exit', function() {
-  assert.ok(writeEndOk);
-});
-
+(function() {
+  var file = path.join(common.tmpDir, 'write-end-test1.txt');
+  var stream = fs.createWriteStream(file);
+  stream.end('a\n', 'utf8');
+  stream.on('close', common.mustCall(function() {
+    var content = fs.readFileSync(file, 'utf8');
+    assert.equal(content, 'a\n');
+  }));
+})();