unified: Unify more fields

Not entirely happy about the mixed nature of the `kind` filed (having
both tokens and the named node `throw_keyword` in there), but that's a
problem for a different time.

unified/extractor/tree-sitter-swift/grammar.js

@@ -1266,7 +1266,10 @@ module.exports = grammar({
       ),
     control_transfer_statement: ($) =>
       choice(
-        prec.right(PRECS.control_transfer, $._throw_statement),
+        prec.right(
+          PRECS.control_transfer,
+          seq(field("kind", $.throw_keyword), field("result", $.expression))
+        ),
         prec.right(
           PRECS.control_transfer,
           seq(

unified/extractor/tree-sitter-swift/node-types.yml

@@ -220,8 +220,7 @@ named:
     lambda*: lambda_literal
     name*: simple_identifier
   control_transfer_statement:
-    $children*: [expression, throw_keyword]
-    kind?: ["break", "continue", "return", "yield"]
+    kind: ["break", "continue", "return", throw_keyword, "yield"]
     result?: expression
   custom_operator:
   default_keyword: