cue/ast/astutil: remove quoted identifiers remnant

I missed this TODO in the cleanup at https://cuelang.org/cl/1185684.
Simplify the double type assertion as well.

Signed-off-by: Daniel Martí <[email protected]>
Change-Id: I144e173656d135617693ecec970bb0b325b37ff7
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1194005
Unity-Result: CUE porcuepine <[email protected]>
Reviewed-by: Roger Peppe <[email protected]>
TryBot-Result: CUEcueckoo <[email protected]>

Author: mvdan

cue/ast/astutil/resolve.go

@@ -122,13 +122,9 @@ func newScope(f *ast.File, outer *scope, node ast.Node, decls []ast.Decl) *scope
 			label := x.Label
 
 			if a, ok := x.Label.(*ast.Alias); ok {
-				// TODO(legacy): use name := a.Ident.Name once quoted
-				// identifiers are no longer supported.
-				label, _ = a.Expr.(ast.Label)
-				if name, _, _ := ast.LabelName(a.Ident); name != "" {
-					if _, ok := label.(*ast.ListLit); !ok {
-						s.insert(name, x, a)
-					}
+				name := a.Ident.Name
+				if _, ok := a.Expr.(*ast.ListLit); !ok {
+					s.insert(name, x, a)
 				}
 			}