fixup! fs: add c++ fast path for writeFileSync utf8

Author: CanadaHonk

benchmark/fs/bench-writeFileSync.js

@@ -8,12 +8,12 @@ tmpdir.refresh();
 const bench = common.createBenchmark(main, {
   encoding: ['utf8'],
   hasFileDescriptor: ['true', 'false'],
-  stringLength: [1024, 4096, 65535],
-  // stringLength: [1024, 4096, 65535, 1024 * 1024],
+  stringLength: [1024, 4096, 65535, 1024 * 1024],
+  func: [ 'writeFile', 'appendFile' ],
   n: [1e3],
 });
 
-function main({ n, encoding, stringLength, hasFileDescriptor }) {
+function main({ n, func, encoding, stringLength, hasFileDescriptor }) {
   tmpdir.refresh();
   const enc = encoding === 'undefined' ? undefined : encoding;
   const path = tmpdir.resolve(`.writefilesync-file-${Date.now()}`);
@@ -23,9 +23,11 @@ function main({ n, encoding, stringLength, hasFileDescriptor }) {
 
   const data = 'a'.repeat(stringLength);
 
+  const fn = fs[func + 'Sync'];
+
   bench.start();
   for (let i = 0; i < n; ++i) {
-    fs.writeFileSync(file, data, enc);
+    fn(file, data, enc);
   }
   bench.end(n);