Implement the new fields for subscript and superscript.

src/types/object.rs

@@ -264,6 +264,8 @@ pub struct StatisticsCookie<'s> {
 pub struct Subscript<'s> {
     pub source: &'s str,
     pub use_brackets: bool,
+    pub contents: &'s str,
+    pub post_blank: Option<&'s str>,
     pub children: Vec<Object<'s>>,
 }
 
@@ -271,6 +273,8 @@ pub struct Subscript<'s> {
 pub struct Superscript<'s> {
     pub source: &'s str,
     pub use_brackets: bool,
+    pub contents: &'s str,
+    pub post_blank: Option<&'s str>,
     pub children: Vec<Object<'s>>,
 }
 
@@ -883,11 +887,15 @@ impl<'s> StandardProperties<'s> for Subscript<'s> {
     }
 
     fn get_contents<'b>(&'b self) -> Option<&'s str> {
-        todo!()
+        Some(self.contents)
     }
 
     fn get_post_blank(&self) -> PostBlank {
-        todo!()
+        self.post_blank
+            .map(|text| text.chars().count())
+            .unwrap_or(0)
+            .try_into()
+            .expect("Too much post-blank to fit into a PostBlank.")
     }
 }
 
@@ -897,11 +905,15 @@ impl<'s> StandardProperties<'s> for Superscript<'s> {
     }
 
     fn get_contents<'b>(&'b self) -> Option<&'s str> {
-        todo!()
+        Some(self.contents)
     }
 
     fn get_post_blank(&self) -> PostBlank {
-        todo!()
+        self.post_blank
+            .map(|text| text.chars().count())
+            .unwrap_or(0)
+            .try_into()
+            .expect("Too much post-blank to fit into a PostBlank.")
     }
 }