Remove setting cancelBubble to false.

third_party/WebKit/Source/core/events/Event.cpp

 /*
  * Copyright (C) 2001 Peter Kelly (pmk@post.com)
  * Copyright (C) 2001 Tobias Anton (anton@stud.fbi.fh-darmstadt.de)
  * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2003, 2005, 2006, 2008 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 69 matching lines @@
              TimeTicks platformTimeStamp)
     : m_type(eventType),
       m_canBubble(canBubbleArg),
       m_cancelable(cancelableArg),
       m_composed(composedMode == ComposedMode::Composed),
       m_isEventTypeScopedInV0(isEventTypeScopedInV0(eventType)),
       m_propagationStopped(false),
       m_immediatePropagationStopped(false),
       m_defaultPrevented(false),
       m_defaultHandled(false),
-      m_cancelBubble(false),
       m_wasInitialized(true),
       m_isTrusted(false),
       m_preventDefaultCalledOnUncancelableEvent(false),
       m_handlingPassive(PassiveMode::NotPassiveDefault),
       m_eventPhase(0),
       m_currentTarget(nullptr),
       m_platformTimeStamp(platformTimeStamp) {}
 
 Event::Event(const AtomicString& eventType, const EventInit& initializer)
     : Event(eventType,
@@ skipping 229 matching lines @@
         DOMWindowPerformance::performance(*scriptState->domWindow());
     double timestampSeconds = (m_platformTimeStamp - TimeTicks()).InSecondsF();
     timeStamp =
         performance->monotonicTimeToDOMHighResTimeStamp(timestampSeconds);
   }
 
   return timeStamp;
 }
 
 void Event::setCancelBubble(ExecutionContext* context, bool cancel) {
-  if (!m_cancelBubble && cancel)
-    UseCounter::count(context, UseCounter::EventCancelBubbleWasChangedToTrue);
-  else if (m_cancelBubble && !cancel)
-    UseCounter::count(context, UseCounter::EventCancelBubbleWasChangedToFalse);
-  m_cancelBubble = cancel;
+  if (cancel)
+    m_propagationStopped = true;
 }
 
 DEFINE_TRACE(Event) {
   visitor->trace(m_currentTarget);
   visitor->trace(m_target);
   visitor->trace(m_underlyingEvent);
   visitor->trace(m_eventPath);
 }
 
 }  // namespace blink