code: function isUnknownMutation(mutation) {
                      var attributeName = mutation.attributeName;
                      var mutationTarget = mutation.target;
                      var mutationType = mutation.type;
                      var strClosest = 'closest';
  
                      if (mutationTarget === _contentElementNative)
                          return attributeName === null;
                      if (mutationType === 'attributes' && (attributeName === LEXICON.c || attributeName === LEXICON.s) && !_isTextarea) {
                          //ignore className changes by the plugin
                          if (attributeName === LEXICON.c && FRAMEWORK(mutationTarget).hasClass(_classNameHostElement))
                              return hostClassNamesChanged(mutation.oldValue, mutationTarget.getAttribute(LEXICON.c));
  
                          //only do it of browser support it natively
                          if (typeof mutationTarget[strClosest] != TYPES.f)
                              return true;
                          if (mutationTarget[strClosest](_strDot + _classNameResizeObserverElement) !== null ||
                              mutationTarget[strClosest](_strDot + _classNameScrollbar) !== null ||
                              mutationTarget[strClosest](_strDot + _classNameScrollbarCorner) !== null)
                              return false;
                      }
                      return true;
                  }
docs: Returns true if the given mutation is not from a from the plugin generated element. If the target element is a textarea the mutation is always unknown.
  @param mutation The mutation which shall be checked.
  @returns {boolean} True if the mutation is from a unknown element, false otherwise.