Remove the io::Decorator trait

This is just an unnecessary trait that no one's ever going to parameterize over
and it's more useful to just define the methods directly on the types
themselves. The implementors of this type almost always don't want
inner_mut_ref() but they're forced to define it as well.

src/libextra/json.rs

@@ -21,7 +21,6 @@ use std::cast::transmute;
 use std::f64;
 use std::hashmap::HashMap;
 use std::io;
-use std::io::Decorator;
 use std::io::mem::MemWriter;
 use std::num;
 use std::str;
@@ -464,7 +463,7 @@ impl Json{
     pub fn to_pretty_str(&self) -> ~str {
         let mut s = MemWriter::new();
         self.to_pretty_writer(&mut s as &mut io::Writer);
-        str::from_utf8_owned(s.inner())
+        str::from_utf8_owned(s.unwrap())
     }
 }
 
@@ -1321,7 +1320,7 @@ impl to_str::ToStr for Json {
     fn to_str(&self) -> ~str {
         let mut s = MemWriter::new();
         self.to_writer(&mut s as &mut io::Writer);
-        str::from_utf8_owned(s.inner())
+        str::from_utf8_owned(s.unwrap())
     }
 }
 
@@ -1508,12 +1507,11 @@ mod tests {
 
     fn with_str_writer(f: |&mut io::Writer|) -> ~str {
         use std::io::mem::MemWriter;
-        use std::io::Decorator;
         use std::str;
 
         let mut m = MemWriter::new();
         f(&mut m as &mut io::Writer);
-        str::from_utf8_owned(m.inner())
+        str::from_utf8_owned(m.unwrap())
     }
 
     #[test]