Sync the DOMSettableTokenList interface with the spec

Source/core/dom/DOMSettableTokenList.idl

Index: Source/core/dom/DOMSettableTokenList.idl
diff --git a/Source/core/dom/DOMSettableTokenList.idl b/Source/core/dom/DOMSettableTokenList.idl
index e65f383d0731db8f769efb948f9cec14d7514e75..b62d9033b7a1390bcf3bbfdbfa6ccb150f9b8faf 100644
--- a/Source/core/dom/DOMSettableTokenList.idl
+++ b/Source/core/dom/DOMSettableTokenList.idl
@@ -22,8 +22,11 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+// https://dom.spec.whatwg.org/#interface-domsettabletokenlist
+
 interface DOMSettableTokenList : DOMTokenList {
-    [ImplementedAs=item] getter DOMString? (unsigned long index);
     attribute DOMString value;
-};
 
+    // FIXME: This getter is not in the spec.
+    [ImplementedAs=item] getter DOMString? (unsigned long index);
+};