buffer: retun fastbuffer directly instead of buffer.alloc(0)

Author: gurgunday

lib/buffer.js

@@ -348,13 +348,13 @@ Buffer.copyBytesFrom = function copyBytesFrom(view, offset, length) {
 
   const viewLength = TypedArrayPrototypeGetLength(view);
   if (viewLength === 0) {
-    return Buffer.alloc(0);
+    return new FastBuffer();
   }
 
   if (offset !== undefined || length !== undefined) {
     if (offset !== undefined) {
       validateInteger(offset, 'offset', 0);
-      if (offset >= viewLength) return Buffer.alloc(0);
+      if (offset >= viewLength) return new FastBuffer();
     } else {
       offset = 0;
     }
@@ -1257,7 +1257,7 @@ if (internalBinding('config').hasIntl) {
       throw new ERR_INVALID_ARG_TYPE('source',
                                      ['Buffer', 'Uint8Array'], source);
     }
-    if (source.length === 0) return Buffer.alloc(0);
+    if (source.length === 0) return new FastBuffer();
 
     fromEncoding = normalizeEncoding(fromEncoding) || fromEncoding;
     toEncoding = normalizeEncoding(toEncoding) || toEncoding;