Change getIterator() type hints to Iterator

This change of type hints from Traversable to Iterator avoids static
analysis errors by phan. As described in
https://github.com/phan/phan/blob/master/NEWS.md#11-feb-2018-phan-0112
phan's type system still does not support inferring key types for
Iterable or Traversable.

Author: Silvan-WMDE

src/Entity/ItemIdSet.php

@@ -52,7 +52,7 @@ public function count() {
 	/**
 	 * @see IteratorAggregate::getIterator
 	 *
-	 * @return Traversable|ItemId[]
+	 * @return Iterator|ItemId[]
 	 */
 	public function getIterator() {
 		return new ArrayIterator( $this->ids );

src/ReferenceList.php

@@ -298,7 +298,7 @@ public function count() {
 	 *
 	 * @since 5.0
 	 *
-	 * @return Traversable
+	 * @return Iterator|Reference[]
 	 */
 	public function getIterator() {
 		return new ArrayIterator( array_values( $this->references ) );

src/SiteLinkList.php

@@ -103,7 +103,7 @@ public function setNewSiteLink( $siteId, $pageName, $badges = null ) {
 	 *
 	 * Returns a Traversable of SiteLink in which the keys are the site ids.
 	 *
-	 * @return Traversable|SiteLink[]
+	 * @return Iterator|SiteLink[]
 	 */
 	public function getIterator() {
 		return new ArrayIterator( $this->siteLinks );

src/Statement/StatementByGuidMap.php

@@ -107,7 +107,7 @@ public function count() {
 	 * The iterator has the GUIDs of the statements as keys.
 	 *
 	 * @see IteratorAggregate::getIterator
-	 * @return Traversable|Statement[]
+	 * @return Iterator|Statement[]
 	 */
 	public function getIterator() {
 		return new ArrayIterator( $this->statements );

src/Statement/StatementList.php

@@ -240,7 +240,7 @@ public function getMainSnaks() {
 	}
 
 	/**
-	 * @return Traversable|Statement[]
+	 * @return Iterator|Statement[]
 	 */
 	public function getIterator() {
 		return new ArrayIterator( $this->statements );

src/Term/AliasGroupList.php

@@ -52,7 +52,7 @@ public function count() {
 
 	/**
 	 * @see IteratorAggregate::getIterator
-	 * @return Traversable|AliasGroup[]
+	 * @return Iterator|AliasGroup[]
 	 */
 	public function getIterator() {
 		return new ArrayIterator( $this->groups );