Fix % string literal with operator

For example, %*string* is changed to %Q*string*.
It's equivalent string literal to be sure,
but this is not good for source code in HTML.
This commit fixes it.

Author: aycabta

lib/rdoc/ruby_lex.rb

@@ -1211,7 +1211,7 @@ def identify_string(ltype, quoted = ltype, type = nil)
     str = if ltype == quoted and %w[" ' /].include? ltype then
             ltype.dup
           else
-            "%#{type or PERCENT_LTYPE.key ltype}#{PERCENT_PAREN_REV[quoted]||quoted}"
+            "%#{type}#{PERCENT_PAREN_REV[quoted]||quoted}"
           end
 
     subtype = nil

test/test_rdoc_parser_ruby.rb

@@ -2838,7 +2838,7 @@ def test_sanity_interpolation_crazy
   def test_sanity_interpolation_curly
     util_parser '%{ #{} }'
 
-    assert_equal '%Q{ #{} }', @parser.get_tk.text
+    assert_equal '%{ #{} }', @parser.get_tk.text
     assert_equal RDoc::RubyToken::TkNL, @parser.get_tk.class
   end