remove outdated comment

compiler/rustc_trait_selection/src/traits/normalize.rs

@@ -21,7 +21,7 @@ pub trait NormalizeExt<'tcx> {
 
     /// Deeply normalizes `value`, replacing all aliases which can by normalized in
     /// the current environment. In the new solver this errors in case normalization
-    /// fails or is ambiguous. This only normalizes opaque types with `Reveal::All`.
+    /// fails or is ambiguous.
     ///
     /// In the old solver this simply uses `normalizes` and adds the nested obligations
     /// to the `fulfill_cx`. This is necessary as we otherwise end up recomputing the