Conditionally define PersistentNode destructor.

third_party/WebKit/Source/platform/heap/PersistentNode.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef PersistentNode_h
 #define PersistentNode_h
 
 #include "platform/PlatformExport.h"
 #include "platform/heap/ThreadState.h"
 #include "wtf/Allocator.h"
 #include "wtf/Assertions.h"
 #include "wtf/MainThread.h"
 #include "wtf/ThreadingPrimitives.h"
 
 namespace blink {
 
 class CrossThreadPersistentRegion;
 
 class PersistentNode final {
     DISALLOW_NEW();
 public:
     PersistentNode()
         : m_self(nullptr)
         , m_trace(nullptr)
     {
         ASSERT(isUnused());
     }
 
+#if ENABLE(ASSERT)
     ~PersistentNode()
     {
         // If you hit this assert, it means that the thread finished
         // without clearing persistent handles that the thread created.
         // We don't enable the assert for the main thread because the
         // main thread finishes without clearing all persistent handles.
         ASSERT(isMainThread() || isUnused());
     }
+#endif
 
-    // It is dangrous to copy the PersistentNode because it breaks the
+    // It is dangerous to copy the PersistentNode because it breaks the
     // free list.
     PersistentNode& operator=(const PersistentNode& otherref) = delete;
 
     // Ideally the trace method should be virtual and automatically dispatch
     // to the most specific implementation. However having a virtual method
     // on PersistentNode leads to too eager template instantiation with MSVC
     // which leads to include cycles.
     // Instead we call the constructor with a TraceCallback which knows the
     // type of the most specific child and calls trace directly. See
     // TraceMethodDelegate in Visitor.h for how this is done.
@@ skipping 142 matching lines @@
     // We don't make CrossThreadPersistentRegion inherit from PersistentRegion
     // because we don't want to virtualize performance-sensitive methods
     // such as PersistentRegion::allocate/freePersistentNode.
     OwnPtr<PersistentRegion> m_persistentRegion;
     Mutex m_mutex;
 };
 
 } // namespace blink
 
 #endif