Traversing: Don't expose jQuery.dir & jQuery.sibling

jQuery.dir & jQuery.sibling are undocumented internal APIs; they shouldn't
be exposed.

(cherry-picked from f9ef427d35)

Fixes gh-2512
Closes gh-2525

src/traversing/var/dir.js

@@ -0,0 +1,20 @@
+define( [
+	"../../core"
+], function( jQuery ) {
+
+return function( elem, dir, until ) {
+	var matched = [],
+		truncate = until !== undefined;
+
+	while ( ( elem = elem[ dir ] ) && elem.nodeType !== 9 ) {
+		if ( elem.nodeType === 1 ) {
+			if ( truncate && jQuery( elem ).is( until ) ) {
+				break;
+			}
+			matched.push( elem );
+		}
+	}
+	return matched;
+};
+
+} );

src/traversing/var/siblings.js

@@ -0,0 +1,15 @@
+define( function() {
+
+return function( n, elem ) {
+	var matched = [];
+
+	for ( ; n; n = n.nextSibling ) {
+		if ( n.nodeType === 1 && n !== elem ) {
+			matched.push( n );
+		}
+	}
+
+	return matched;
+};
+
+} );