Revert ca608f18f089. rdar://problem/103539448 This reverts commit 65db389fa4b6c49c3c4965b096d68121e8a325a8. Canonical link: https://commits.webkit.org/252432.1015@safari-7614.4.6.2-branch

diff --git a/LayoutTests/fast/scrolling/mac/smooth-scroll-with-overflow-hidden-and-layout-expected.txt b/LayoutTests/fast/scrolling/mac/smooth-scroll-with-overflow-hidden-and-layout-expected.txt
deleted file mode 100644
index f97ab22..0000000
--- a/LayoutTests/fast/scrolling/mac/smooth-scroll-with-overflow-hidden-and-layout-expected.txt
+++ /dev/null

@@ -1,5 +0,0 @@
-PASS scrollContainer.scrollLeft is 500
-PASS successfullyParsed is true
-
-TEST COMPLETE
-

diff --git a/LayoutTests/fast/scrolling/mac/smooth-scroll-with-overflow-hidden-and-layout.html b/LayoutTests/fast/scrolling/mac/smooth-scroll-with-overflow-hidden-and-layout.html
deleted file mode 100644
index 2d85284..0000000
--- a/LayoutTests/fast/scrolling/mac/smooth-scroll-with-overflow-hidden-and-layout.html
+++ /dev/null

@@ -1,60 +0,0 @@
-<!DOCTYPE html> <!-- webkit-test-runner [ AsyncOverflowScrollingEnabled=true ] -->
-<html>
-<head>
-    <style>
-        .scroll-container {
-            height: 250px;
-            width: 300px;
-            border: 1px solid black;
-            overflow: hidden;
-        }
-        
-        .contents {
-            height: 100%;
-            width: 400%;
-            background-image: repeating-linear-gradient(to right, white, silver 250px);
-        }
-        
-        body.changed .contents {
-            height: 120%;
-        }
-    </style>
-    <script src="../../../resources/ui-helper.js"></script>
-    <script src="../../../resources/js-test-pre.js"></script>
-    <script>
-        jsTestIsAsync = true;
-
-        async function runTest()
-        {
-            scrollContainer = document.querySelector('.scroll-container');
-
-            if (window.eventSender)
-                eventSender.monitorWheelEvents();
-            
-            scrollContainer.scrollTo({
-                top: 0,
-                left: 500,
-                behavior: 'smooth'
-            });
-            
-            document.body.classList.add('changed');
-            
-            await UIHelper.waitForScrollCompletion();
-            
-            shouldBe('scrollContainer.scrollLeft', '500');
-            finishJSTest();
-        }
-    
-        window.addEventListener('load', () => {
-            setTimeout(runTest, 0);
-        }, false);
-    </script>
-</head>
-<body>
-    <div class="scroll-container">
-        <div class="contents"></div>
-    </div>
-    <div id="console"></div>
-    <script src="../../../resources/js-test-post.js"></script>
-</body>
-</html>

diff --git a/LayoutTests/fast/scrolling/mac/smooth-scroll-with-overflow-hidden.html b/LayoutTests/fast/scrolling/mac/smooth-scroll-with-overflow-hidden.html
index d146d85..42aa9b4 100644
--- a/LayoutTests/fast/scrolling/mac/smooth-scroll-with-overflow-hidden.html
+++ b/LayoutTests/fast/scrolling/mac/smooth-scroll-with-overflow-hidden.html

@@ -6,6 +6,7 @@
             height: 250px;
             width: 300px;
             border: 1px solid black;
+            overflow-y: scroll;
             overflow: hidden;
         }
         
@@ -24,8 +25,7 @@
         {
             scrollContainer = document.querySelector('.scroll-container');
 
-            if (window.eventSender)
-                eventSender.monitorWheelEvents();
+            eventSender.monitorWheelEvents();
             
             scrollContainer.scrollTo({
                 top: 0,

diff --git a/Source/WebCore/platform/ScrollableArea.h b/Source/WebCore/platform/ScrollableArea.h
index d65887c..c42d338 100644
--- a/Source/WebCore/platform/ScrollableArea.h
+++ b/Source/WebCore/platform/ScrollableArea.h

@@ -451,6 +451,7 @@
     bool m_inLiveResize { false };
     bool m_scrollOriginChanged { false };
     bool m_scrollShouldClearLatchedState { false };
+    bool m_hasActiveScrollAnimation { false };
 };
 
 WTF::TextStream& operator<<(WTF::TextStream&, const ScrollableArea&);

diff --git a/Source/WebCore/rendering/RenderLayerScrollableArea.cpp b/Source/WebCore/rendering/RenderLayerScrollableArea.cpp
index 1c1446f..c75b005 100644
--- a/Source/WebCore/rendering/RenderLayerScrollableArea.cpp
+++ b/Source/WebCore/rendering/RenderLayerScrollableArea.cpp

@@ -1648,10 +1648,10 @@
     if (HTMLFrameOwnerElement* owner = frameView.frame().ownerElement())
         isVisibleToHitTest &= owner->renderer() && owner->renderer()->visibleToHitTesting();
 
-    bool needsToBeRegistered = (hasOverflow && isVisibleToHitTest) || scrollAnimationStatus() == ScrollAnimationStatus::Animating;
+    bool isScrollable = hasOverflow && isVisibleToHitTest;
     bool addedOrRemoved = false;
 
-    if (needsToBeRegistered) {
+    if (isScrollable) {
         if (!m_registeredScrollableArea) {
             addedOrRemoved = frameView.addScrollableArea(this);
             m_registeredScrollableArea = true;