cleanup: thread []*html.Node through winnow, drop temp Selection

winnow only ever reads sel.Nodes; the *Selection parameter was
incidental. Change its signature to winnow(nodes []*html.Node, ...)
and update its three callers (FilterMatcher, NotMatcher,
filterAndPush). filterAndPush no longer needs to fabricate a
throwaway Selection to satisfy the call.

While this change has o measurable runtime effect, it simplifies the code a bit,
by making winnow's signature clearer, and removes a now-useless line and its
associated comment in filterAndPush

filter.go

@@ -12,7 +12,7 @@ func (s *Selection) Filter(selector string) *Selection {
 // the given matcher. It returns a new Selection object for this subset
 // of matching elements.
 func (s *Selection) FilterMatcher(m Matcher) *Selection {
-	return pushStack(s, winnow(s, m, true))
+	return pushStack(s, winnow(s.Nodes, m, true))
 }
 
 // Not removes elements from the Selection that match the selector string.
@@ -24,7 +24,7 @@ func (s *Selection) Not(selector string) *Selection {
 // NotMatcher removes elements from the Selection that match the given matcher.
 // It returns a new Selection object with the matching elements removed.
 func (s *Selection) NotMatcher(m Matcher) *Selection {
-	return pushStack(s, winnow(s, m, false))
+	return pushStack(s, winnow(s.Nodes, m, false))
 }
 
 // FilterFunction reduces the set of matched elements to those that pass the function's test.
@@ -142,14 +142,14 @@ func (s *Selection) End() *Selection {
 
 // Filter based on the matcher, and the indicator to keep (Filter) or
 // to get rid of (Not) the matching elements.
-func winnow(sel *Selection, m Matcher, keep bool) []*html.Node {
+func winnow(nodes []*html.Node, m Matcher, keep bool) []*html.Node {
 	// Optimize if keep is requested
 	if keep {
-		return m.Filter(sel.Nodes)
+		return m.Filter(nodes)
 	}
 	// Not path: call Match directly on each node, no Selection wrapper needed
-	result := make([]*html.Node, 0, len(sel.Nodes))
-	for _, n := range sel.Nodes {
+	result := make([]*html.Node, 0, len(nodes))
+	for _, n := range nodes {
 		if !m.Match(n) {
 			result = append(result, n)
 		}

traversal.go

@@ -537,10 +537,7 @@ func (s *Selection) PrevMatcherUntilNodes(filter Matcher, nodes ...*html.Node) *
 // Filter and push filters the nodes based on a matcher, and pushes the results
 // on the stack, with the srcSel as previous selection.
 func filterAndPush(srcSel *Selection, nodes []*html.Node, m Matcher) *Selection {
-	// Create a temporary Selection with the specified nodes to filter using winnow
-	sel := &Selection{nodes, srcSel.document, nil}
-	// Filter based on matcher and push on stack
-	return pushStack(srcSel, winnow(sel, m, true))
+	return pushStack(srcSel, winnow(nodes, m, true))
 }
 
 // Internal implementation of Find that return raw nodes.