Allow file redirects on while statements

corpus/control_flow.txt

@@ -16,6 +16,24 @@ done
       (command (command_name (word)) (word))
       (command (command_name (word)) (word)))))
 
+====================================
+While statements with IO redirects
+====================================
+
+while read line; do
+  echo $line
+done < <(cat file)
+
+---
+
+(program
+  (while_statement
+    (command (command_name (word)) (word))
+    (do_group
+      (command (command_name (word)) (simple_expansion (variable_name))))
+    (file_redirect (process_substitution
+      (command (command_name (word)) (word))))))
+
 ====================================
 For statements
 ====================================

grammar.js

@@ -78,7 +78,12 @@ module.exports = grammar({
     while_statement: $ => seq(
       'while',
       $._terminated_statement,
-      $.do_group
+      $.do_group,
+      repeat(choice(
+        $.file_redirect,
+        $.heredoc_redirect,
+        $.herestring_redirect
+      ))
     ),
 
     do_group: $ => seq(