1 files changed, 10 insertions, 2 deletions
diff --git a/tests/wpt/web-platform-tests/interfaces/scroll-animations.idl b/tests/wpt/web-platform-tests/interfaces/scroll-animations.idl
index 00d0bae6812..782d08f4c40 100644
--- a/tests/wpt/web-platform-tests/interfaces/scroll-animations.idl
+++ b/tests/wpt/web-platform-tests/interfaces/scroll-animations.idl
@@ -15,8 +15,8 @@ enum ScrollTimelineAutoKeyword { "auto" };
 dictionary ScrollTimelineOptions {
   Element? source = null;
   ScrollDirection orientation = "block";
-  DOMString start = "auto";
-  DOMString end = "auto";
+  (DOMString or ElementBasedOffset) start = "auto";
+  (DOMString or ElementBasedOffset) end = "auto";
   (double or ScrollTimelineAutoKeyword) timeRange = "auto";
 };
 
@@ -29,3 +29,11 @@ interface ScrollTimeline : AnimationTimeline {
   readonly attribute DOMString end;
   readonly attribute (double or ScrollTimelineAutoKeyword) timeRange;
 };
+
+enum Edge { "start", "end" };
+
+dictionary ElementBasedOffset {
+  Element target;
+  Edge edge = "start";
+  double threshold = 0.0;
+};