Remove the overflowchanged event with a runtime flag

Source/core/dom/Document.cpp

Index: Source/core/dom/Document.cpp
diff --git a/Source/core/dom/Document.cpp b/Source/core/dom/Document.cpp
index 102174822335cee8171a17993bea52ee962478d7..a701ceb3085a4a801b2c1f482c5bc8866291626f 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -3849,7 +3849,7 @@ void Document::addListenerTypeIfNeeded(const AtomicString& eventType)
     } else if (eventType == EventTypeNames::DOMCharacterDataModified) {
         UseCounter::count(*this, UseCounter::DOMCharacterDataModifiedEvent);
         addMutationEventListenerTypeIfEnabled(DOMCHARACTERDATAMODIFIED_LISTENER);
-    } else if (eventType == EventTypeNames::overflowchanged) {
+    } else if (eventType == EventTypeNames::overflowchanged && RuntimeEnabledFeatures::overflowChangedEventEnabled()) {
         UseCounter::countDeprecation(*this, UseCounter::OverflowChangedEvent);
         addListenerType(OVERFLOWCHANGED_LISTENER);
     } else if (eventType == EventTypeNames::webkitAnimationStart || (RuntimeEnabledFeatures::cssAnimationUnprefixedEnabled() && eventType == EventTypeNames::animationstart)) {