Remove ResolvableName from Ty1

This is not treated as resolvable for now. It only supports a hardcoded
set of generic types (UniquePtr, CxxVector, Box, Vec).
diff --git a/syntax/mod.rs b/syntax/mod.rs
index 6684b6a..782d617 100644
--- a/syntax/mod.rs
+++ b/syntax/mod.rs
@@ -160,7 +160,7 @@
 }
 
 pub struct Ty1 {
-    pub name: ResolvableName,
+    pub name: Ident,
     pub langle: Token![<],
     pub inner: Type,
     pub rangle: Token![>],