Remove unused func

crates/ra_proc_macro_srv/src/rustc_server.rs

@@ -33,9 +33,7 @@ impl TokenStream {
     pub fn new() -> Self {
         TokenStream { subtree: Default::default() }
     }
-    pub fn with_subtree(subtree: tt::Subtree) -> Self {
-        TokenStream { subtree }
-    }
+
     pub fn is_empty(&self) -> bool {
         self.subtree.token_trees.is_empty()
     }