Gain back 10MB/s on the json deserialization benchmark

serde_json/src/de.rs

@@ -54,9 +54,15 @@ impl<Iter> Deserializer<Iter>
         match self.ch {
             Some(ch) => Ok(Some(ch)),
             None => {
-                self.ch = try!(self.next_char());
+                match self.rdr.next() {
+                    Some(Err(err)) => Err(Error::IoError(err)),
+                    Some(Ok(ch)) => {
+                        self.ch = Some(ch);
                         Ok(self.ch)
                     }
+                    None => Ok(None),
+                }
+            }
         }
     }