Make sure we call .words on stringified var

By taking out the call to Stringy in the infix:<~> handling, any variable
would be directly exposed to having ".words" called upon it in << >>
post-processing.  This works for IO::Paths, but doesn't work for many
other classes:

  $ perl6 -e 'class A {}; my $a = A.new; dd << foo $a >>'
  No such method 'words' for invocant of type 'A'

Fixed this by inserting a stringification for this particular case of
quotewords processing.  Fixes R#2203

src/Perl6/Actions.nqp

@@ -10509,7 +10509,11 @@ class Perl6::QActions is HLL::Actions does STDActions {
                             :op('callmethod'),
                             :name('words'),
                             :node($/),
-                            $node,
+                            QAST::Op.new(
+                                :op('callmethod'),
+                                :name('Stringy'),
+                                $node
+                            ),
                             QAST::IVal.new( :value(1), :named('autoderef') )
                         )
                     )