eventTargetData(): pull (most of) this singleton off-heap.

third_party/WebKit/Source/core/dom/Node.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All
  * rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  *
@@ skipping 1864 matching lines @@
   ScriptForbiddenScope forbidScriptDuringRawIteration;
   for (Node& node : NodeTraversal::startsAt(*this)) {
     node.removeAllEventListeners();
     for (ShadowRoot* root = node.youngestShadowRoot(); root;
          root = root->olderShadowRoot())
       root->removeAllEventListenersRecursively();
   }
 }
 
 using EventTargetDataMap =
-    HeapHashMap<WeakMember<Node>, Member<EventTargetData>>;
+    PersistentHeapHashMap<WeakMember<Node>, Member<EventTargetData>>;
 static EventTargetDataMap& eventTargetDataMap() {
-  DEFINE_STATIC_LOCAL(EventTargetDataMap, map, (new EventTargetDataMap));
+  DEFINE_STATIC_LOCAL(EventTargetDataMap, map, ());
   return map;
 }
 
 EventTargetData* Node::eventTargetData() {
   return hasEventTargetData() ? eventTargetDataMap().get(this) : nullptr;
 }
 
 EventTargetData& Node::ensureEventTargetData() {
   if (hasEventTargetData())
     return *eventTargetDataMap().get(this);
@@ skipping 644 matching lines @@
   if (node) {
     std::stringstream stream;
     node->printNodePathTo(stream);
     LOG(INFO) << stream.str();
   } else {
     LOG(INFO) << "Cannot showNodePath for <null>";
   }
 }
 
 #endif