Simplify begin_header production

The TOK_END is swallowed by the subsequent job_list anyway.

fish_tests.cpp

@@ -891,7 +891,9 @@ static void test_indents()
 
     const indent_component_t components7[] =
     {
-        {L"begin; end", 0},
+        {L"begin", 0},
+        {L";", 1},
+        {L"end", 0},
         {L"foo", 0},
         {L"", 0},
         {NULL, -1}

parse_productions.cpp

@@ -341,18 +341,9 @@ RESOLVE_ONLY(while_header)
 
 PRODUCTIONS(begin_header) =
 {
-    {KEYWORD(parse_keyword_begin), parse_token_type_end},
     {KEYWORD(parse_keyword_begin)}
 };
-RESOLVE(begin_header)
-{
-    switch (token2.type) {
-        case parse_token_type_end:
-            return 0;
-        default:
-            return 1;
-    }
-}
+RESOLVE_ONLY(begin_header)
 
 PRODUCTIONS(function_header) =
 {

parse_tree.h

@@ -253,7 +253,7 @@ bool parse_tree_from_string(const wcstring &str, parse_tree_flags_t flags, parse
     block_header = for_header | while_header  | function_header | begin_header
     for_header = FOR var_name IN argument_list <TOK_END>
     while_header = WHILE job <TOK_END>
-    begin_header = BEGIN | BEGIN <TOK_END>
+    begin_header = BEGIN
 
 # Functions take arguments, and require at least one (the name). No redirections allowed.
     function_header = FUNCTION argument argument_list <TOK_END>