[ruby/cgi] Skip unless CGI::EscapeExt methods are implemented

ruby/cgi@7b5a13952b

Author: nobu

test/cgi/test_cgi_escape.rb

@@ -300,7 +300,7 @@ def setup
       remove_method :escapeHTML
       alias _unescapeHTML unescapeHTML
       remove_method :unescapeHTML
-    end if defined?(CGI::EscapeExt)
+    end if defined?(CGI::EscapeExt) and CGI::EscapeExt.method_defined?(:escapeHTML)
   end
 
   def teardown
@@ -309,7 +309,7 @@ def teardown
       remove_method :_escapeHTML
       alias unescapeHTML _unescapeHTML
       remove_method :_unescapeHTML
-    end if defined?(CGI::EscapeExt)
+    end if defined?(CGI::EscapeExt) and CGI::EscapeExt.method_defined?(:_escapeHTML)
   end
 
   include CGIEscapeTest::UnescapeHTMLTests