Fix handling complex expression in for/while/until

The parse_statements method calls
skip_optional_do_after_expression method
in case of for/while/until tokens.
The skip_optional_do_after_expression method uses get_end_token method
for checking end of loop condition expressions,
but it's not correct,
because the end is detected by only
"do" token, newline and semi-colon token.
This commit fixes it.

Author: aycabta

lib/rdoc/parser/ruby.rb

@@ -2022,31 +2022,25 @@ def scan
   def skip_optional_do_after_expression
     skip_tkspace false
     tk = get_tk
-    end_token = get_end_token tk
 
     b_nest = 0
     nest = 0
     @scanner.continue = false
 
     loop do
       case tk
-      when TkSEMICOLON then
+      when TkSEMICOLON, TkNL then
         break if b_nest.zero?
       when TkLPAREN, TkfLPAREN then
         nest += 1
+      when TkRPAREN then
+        nest -= 1
       when TkBEGIN then
         b_nest += 1
       when TkEND then
         b_nest -= 1
       when TkDO
         break if nest.zero?
-      when end_token then
-        if end_token == TkRPAREN
-          nest -= 1
-          break if @scanner.lex_state == :EXPR_END and nest.zero?
-        else
-          break unless @scanner.continue
-        end
       when nil then
         break
       end