Separate babel call out to its own parser.

src/types/lesser_element.rs

@@ -138,7 +138,6 @@ pub struct Keyword<'s> {
 pub struct BabelCall<'s> {
     pub source: &'s str,
     pub name: Option<&'s str>,
-    pub key: &'s str,
     pub value: &'s str,
 }