Introduce WebRange::isEmpty.

third_party/WebKit/public/web/WebRange.h

 /*
  * 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 35 matching lines @@
 class WebRange final {
 public:
     BLINK_EXPORT WebRange(int start, int length);
     BLINK_EXPORT WebRange() {}
 
     int startOffset() const { return m_start; }
     int endOffset() const { return m_end; }
     int length() const { return m_end - m_start; }
 
     bool isNull() const { return m_start == -1 && m_end == -1; }
+    bool isEmpty() const { return m_start == m_end; }
 
 #if BLINK_IMPLEMENTATION
     WebRange(const EphemeralRange&);
     WebRange(const PlainTextRange&);
 
     EphemeralRange createEphemeralRange(LocalFrame*) const;
 #endif
 
 private:
     // Note that this also matches the values for gfx::Range::InvalidRange
     // for easy conversion.
     int m_start = -1;
     int m_end = -1;
 };
 
 } // namespace blink
 
 #endif