Move constants into NodeTraverser class

Not that the interface makes much sense anyway, but these are
implementation details of a specific traverser.

Author: nikic

lib/PhpParser/NodeTraverser.php

@@ -4,6 +4,24 @@
 
 class NodeTraverser implements NodeTraverserInterface
 {
+    /**
+     * If NodeVisitor::enterNode() returns DONT_TRAVERSE_CHILDREN, child nodes
+     * of the current node will not be traversed for any visitors.
+     *
+     * For subsequent visitors enterNode() will still be called on the current
+     * node and leaveNode() will also be invoked for the current node.
+     */
+    const DONT_TRAVERSE_CHILDREN = 1;
+
+    /**
+     * If NodeVisitor::leaveNode() returns REMOVE_NODE for a node that occurs
+     * in an array, it will be removed from the array.
+     *
+     * For subsequent visitors leaveNode() will still be invoked for the
+     * removed node.
+     */
+    const REMOVE_NODE = false;
+
     /** @var NodeVisitor[] Visitors */
     protected $visitors;
 

lib/PhpParser/NodeTraverserInterface.php

@@ -4,24 +4,6 @@
 
 interface NodeTraverserInterface
 {
-    /**
-     * If NodeVisitor::enterNode() returns DONT_TRAVERSE_CHILDREN, child nodes
-     * of the current node will not be traversed for any visitors.
-     *
-     * For subsequent visitors enterNode() will still be called on the current
-     * node and leaveNode() will also be invoked for the current node.
-     */
-    const DONT_TRAVERSE_CHILDREN = 1;
-
-    /**
-     * If NodeVisitor::leaveNode() returns REMOVE_NODE for a node that occurs
-     * in an array, it will be removed from the array.
-     *
-     * For subsequent visitors leaveNode() will still be invoked for the
-     * removed node.
-     */
-    const REMOVE_NODE = false;
-
     /**
      * Adds a visitor.
      *