Add KeyedTraversable interface

hphp/system/classes/iterator.php

@@ -103,6 +103,9 @@ interface JsonSerializable {
 interface Traversable {
 }
 
+interface KeyedTraversable extends Traversable {
+}
+
 // Do NOT modifiy this doc comment block generated by idl/sysdoc.php
 /**
  * ( excerpt from http://php.net/manual/en/class.iterator.php )
@@ -167,7 +170,7 @@ interface Iterator extends Traversable {
   public function valid();
 }
 
-interface KeyedIterator extends Iterator {
+interface KeyedIterator extends Iterator, KeyedTraversable {
 }
 
 // Do NOT modifiy this doc comment block generated by idl/sysdoc.php
@@ -792,7 +795,7 @@ interface IteratorAggregate extends Traversable {
 interface Iterable extends IteratorAggregate {
 }
 
-interface KeyedIterable extends Iterable {
+interface KeyedIterable extends Iterable, KeyedTraversable {
 }
 
 ///////////////////////////////////////////////////////////////////////////////