Add keys(), values() and entries() methods on iterable<> interfaces

LayoutTests/fast/js/iterable-object.html

Index: LayoutTests/fast/js/iterable-object.html
diff --git a/LayoutTests/fast/js/iterable-object.html b/LayoutTests/fast/js/iterable-object.html
index 0aa4b231718dd0e99f1f6ac6d35b3a093f640a18..70e481af7491b1f4fe2aaafb565767a8d754e52c 100644
--- a/LayoutTests/fast/js/iterable-object.html
+++ b/LayoutTests/fast/js/iterable-object.html
@@ -16,6 +16,18 @@ for (var value of internals[Symbol.iterator]()) {
     debug('value = ' + value);
 }
 
+for (var key of internals.keys()) {
+    debug('key = ' + key);
+}
+
+for (var value of internals.values()) {
+    debug('value = ' + value);
+}
+
+for (var entry of internals.entries()) {
+    debug('entry = ' + entry);
+}
+
 </script>
 </body>
 </html>