Remove comments about omitting None values

Author: webmaster128

src/ser/mod.rs

@@ -952,7 +952,6 @@ mod tests {
             description: Some("An ambient temperature sensor"),
         });
 
-        // XXX Ideally this should produce "{}"
         assert_eq!(
             to_string(&Property { description: None }).unwrap(),
             r#"{"description":null}"#

src/ser/struct_.rs

@@ -21,7 +21,6 @@ impl<'a> ser::SerializeStruct for SerializeStruct<'a> {
     where
         T: ser::Serialize,
     {
-        // XXX if `value` is `None` we not produce any output for this field
         if !self.first {
             self.ser.buf.push(b',');
         }
@@ -50,7 +49,6 @@ impl<'a> ser::SerializeStructVariant for SerializeStruct<'a> {
     where
         T: ser::Serialize,
     {
-        // XXX if `value` is `None` we not produce any output for this field
         if !self.first {
             self.ser.buf.push(b',');
         }