refactor(serialization): remove extra copy in serializeWithBufferAndIndex

Author: xaviergonz

lib/bson/bson.js

@@ -93,15 +93,14 @@ BSON.prototype.serializeWithBufferAndIndex = function(object, finalBuffer, optio
 
   // Attempt to serialize
   var serializationIndex = serializer(
-    buffer,
+    finalBuffer,
     object,
     checkKeys,
     0,
     0,
     serializeFunctions,
     ignoreUndefined
   );
-  buffer.copy(finalBuffer, startIndex, 0, serializationIndex);
 
   // Return the index
   return startIndex + serializationIndex - 1;