Allow for statements without in clauses

corpus/statements.txt

@@ -42,6 +42,11 @@ for a in 1 2 $(seq 5 10); do
   echo $a
 done
 
+for ARG; do
+  echo $ARG
+  ARG=''
+done
+
 ---
 
 (program
@@ -51,7 +56,12 @@ done
     (word)
     (command_substitution (command (command_name (word)) (word) (word)))
     (do_group
-      (command (command_name (word)) (simple_expansion (variable_name))))))
+      (command (command_name (word)) (simple_expansion (variable_name)))))
+  (for_statement
+    (variable_name)
+    (do_group
+      (command (command_name (word)) (simple_expansion (variable_name)))
+      (variable_assignment (variable_name) (raw_string)))))
 
 ====================================
 If statements

grammar.js

@@ -71,8 +71,10 @@ module.exports = grammar({
     for_statement: $ => seq(
       'for',
       $._simple_variable_name,
-      'in',
-      repeat1($._expression),
+      optional(seq(
+        'in',
+        repeat1($._expression)
+      )),
       $._terminator,
       $.do_group
     ),

script/known-failures.txt

@@ -1,9 +1,7 @@
 examples/bash-it/plugins/available/git.plugin.bash
 examples/bash-it/plugins/available/extract.plugin.bash
-examples/bash-it/plugins/available/less-pretty-cat.plugin.bash
 examples/bash-it/plugins/available/z_autoenv.plugin.bash
 examples/bash-it/plugins/available/sshagent.plugin.bash
-examples/bash-it/plugins/available/gif.plugin.bash
 examples/bash-it/plugins/available/go.plugin.bash
 examples/bash-it/plugins/available/proxy.plugin.bash
 examples/bash-it/plugins/available/browser.plugin.bash

src/grammar.json

@@ -90,15 +90,28 @@
           "name": "_simple_variable_name"
         },
         {
-          "type": "STRING",
-          "value": "in"
-        },
-        {
-          "type": "REPEAT1",
-          "content": {
-            "type": "SYMBOL",
-            "name": "_expression"
-          }
+          "type": "CHOICE",
+          "members": [
+            {
+              "type": "SEQ",
+              "members": [
+                {
+                  "type": "STRING",
+                  "value": "in"
+                },
+                {
+                  "type": "REPEAT1",
+                  "content": {
+                    "type": "SYMBOL",
+                    "name": "_expression"
+                  }
+                }
+              ]
+            },
+            {
+              "type": "BLANK"
+            }
+          ]
         },
         {
           "type": "SYMBOL",