Update DCHECK in WebRange constructor.

third_party/WebKit/Source/web/WebRange.cpp

 /*
  * Copyright (C) 2009 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 24 matching lines @@
 #include "core/editing/FrameSelection.h"
 #include "core/editing/PlainTextRange.h"
 #include "core/frame/LocalFrame.h"
 
 namespace blink {
 
 WebRange::WebRange(int start, int length)
     : m_start(start)
     , m_end(start + length)
 {
-    DCHECK(start != -1 && length != 0) << "These values are reserved to indicate that the range is null";
+    DCHECK(start != -1 || length != 0) << "These values are reserved to indicate that the range is null";
 }
 
 WebRange::WebRange(const EphemeralRange& range)
 {
     if (range.isNull())
         return;
 
     m_start = range.startPosition().computeOffsetInContainerNode();
     m_end =range.endPosition().computeOffsetInContainerNode();
 }
 
 WebRange::WebRange(const PlainTextRange& range)
 {
     if (range.isNull())
         return;
 
     m_start = range.start();
     m_end = range.end();
 }
 
 EphemeralRange WebRange::createEphemeralRange(LocalFrame* frame) const
 {
     Element* selectionRoot = frame->selection().rootEditableElement();
     ContainerNode* scope = selectionRoot ? selectionRoot : frame->document()->documentElement();
 
     return PlainTextRange(m_start, m_end).createRange(*scope);
 }
 
 } // namespace blink