rustdoc: Remove single-use Lifetime::get_ref() function

src/librustdoc/clean/types.rs

@@ -1207,10 +1207,6 @@ impl GenericBound {
 crate struct Lifetime(pub Symbol);
 
 impl Lifetime {
-    crate fn get_ref(&self) -> SymbolStr {
-        self.0.as_str()
-    }
-
     crate fn statik() -> Lifetime {
         Lifetime(kw::StaticLifetime)
     }

src/librustdoc/html/format.rs

@@ -346,7 +346,7 @@ impl clean::Generics {
 
 impl clean::Lifetime {
     crate fn print(&self) -> impl fmt::Display + '_ {
-        self.get_ref()
+        self.0.as_str()
     }
 }