fix(pat scroll box): Fix issue where elastic scrolling on Safari would remove the scroll-position-top class for a moment when overscrolling on top.

Author: thet

src/pat/scroll-box/scroll-box.js

@@ -69,7 +69,7 @@ export default Base.extend({
             to_add.push("scrolling-down");
         }
 
-        if (scroll_pos === 0) {
+        if (scroll_pos <= 0) {
             to_add.push("scroll-position-top");
         } else if (
             this.scroll_listener === window &&

src/pat/scroll-box/scroll-box.test.js

@@ -69,6 +69,16 @@ describe("pat-scroll-box", function () {
         expect(el.classList).not.toContain("scrolling-up");
         expect(el.classList).toContain("scrolling-down");
 
+        el.scrollTop = 250; // overscrolling / elastic scrolling in Safari
+        el.dispatchEvent(events.scroll_event());
+        await utils.animation_frame();
+        expect(el.classList).not.toContain("scroll-position-top");
+        expect(el.classList).toContain("scroll-position-bottom");
+        expect(el.classList).not.toContain("scroll-up");
+        expect(el.classList).toContain("scroll-down");
+        expect(el.classList).not.toContain("scrolling-up");
+        expect(el.classList).toContain("scrolling-down");
+
         el.scrollTop = 0;
         el.dispatchEvent(events.scroll_event());
         await utils.animation_frame();
@@ -79,6 +89,16 @@ describe("pat-scroll-box", function () {
         expect(el.classList).toContain("scrolling-up");
         expect(el.classList).not.toContain("scrolling-down");
 
+        el.scrollTop = -50; // overscrolling / elastic scrolling in Safari
+        el.dispatchEvent(events.scroll_event());
+        await utils.animation_frame();
+        expect(el.classList).toContain("scroll-position-top");
+        expect(el.classList).not.toContain("scroll-position-bottom");
+        expect(el.classList).toContain("scroll-up");
+        expect(el.classList).not.toContain("scroll-down");
+        expect(el.classList).toContain("scrolling-up");
+        expect(el.classList).not.toContain("scrolling-down");
+
         // Test for clearing the scrolling classes after a scroll stop
         // scroll-up and scroll-down are not cleared.