Rollup merge of #110203 - compiler-errors:rtn-dots, r=eholk

Remove `..` from return type notation

`@nikomatsakis` and I decided that using `..` in the return-type notation syntax is probably overkill.

r? `@eholk` since you reviewed the last one

Since this is piggybacking now totally off of a pre-existing syntax (parenthesized generics), let me know if you need any explanation of the logic here, since it's a bit more complicated now.

compiler/rustc_passes/src/hir_stats.rs

@@ -666,7 +666,7 @@ impl<'v> ast_visit::Visitor<'v> for StatCollector<'v> {
     fn visit_generic_args(&mut self, g: &'v ast::GenericArgs) {
         record_variants!(
             (self, g, g, Id::None, ast, GenericArgs, GenericArgs),
-            [AngleBracketed, Parenthesized, ReturnTypeNotation]
+            [AngleBracketed, Parenthesized]
         );
         ast_visit::walk_generic_args(self, g)
     }