message: Reuse IsEmpty for ConstString::operator bool().
diff: @@ -140,7 +140,7 @@ public:
  /// /b True this object contains a valid non-empty C string, \b
  /// false otherwise.
  //------------------------------------------------------------------
  - explicit operator bool() const { return m_string && m_string[0]; }
  + explicit operator bool() const { return !IsEmpty(); }
  //------------------------------------------------------------------
  /// Assignment operator
  