Replace ENABLE(ASSERT) with DCHECK_IS_ON().

third_party/WebKit/Source/core/html/parser/HTMLTreeBuilder.h

 /*
  * Copyright (C) 2010 Google, Inc. All Rights Reserved.
  * Copyright (C) 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 227 matching lines @@
 
     DECLARE_TRACE();
 
    private:
     Member<DocumentFragment> m_fragment;
     Member<HTMLStackItem> m_contextElementStackItem;
   };
 
   // https://html.spec.whatwg.org/#frameset-ok-flag
   bool m_framesetOk;
-#if ENABLE(ASSERT)
-  bool m_isAttached;
+#if DCHECK_IS_ON()
+  bool m_isAttached = true;
 #endif
   FragmentParsingContext m_fragmentContext;
   HTMLConstructionSite m_tree;
 
   // http://www.whatwg.org/specs/web-apps/current-work/multipage/parsing.html#insertion-mode
   InsertionMode m_insertionMode;
 
   // http://www.whatwg.org/specs/web-apps/current-work/multipage/parsing.html#original-insertion-mode
   InsertionMode m_originalInsertionMode;
 
@@ skipping 14 matching lines @@
 
   // Starting line number of the script tag needing processing.
   TextPosition m_scriptToProcessStartPosition;
 
   HTMLParserOptions m_options;
 };
 
 }  // namespace blink
 
 #endif