docs: function getHTMLElementContentRect(target) {
      // Client width & height properties can't be
      // used exclusively as they provide rounded values.
      const {clientWidth, clientHeight} = target;
  
      // By this condition we can catch all non-replaced inline, hidden and
      // detached elements. Though elements with width & height properties less
      // than 0.5 will be discarded as well.
      //
      // Without it we would need to implement separate methods for each of
      // those cases and it's not possible to perform a precise and performance
      // effective test for hidden elements. E.g. even jQuery's ':visible' filter
      // gives wrong results for elements with width & height less than 0.5.
      if (!clientWidth && !clientHeight) {
          return emptyRect;
      }
  
      const styles = getWindowOf(target).getComputedStyle(target);
      const paddings = getPaddings(styles);
      const horizPad = paddings.left + paddings.right;
      const vertPad = paddings.top + paddings.bottom;
  
      // Computed styles of width & height are being used because they are the
      // only dimensions available to JS that contain non-rounded values. It could
      // be possible to utilize the getBoundingClientRect if only it's data wasn't
      // affected by CSS transformations let alone paddings, borders and scroll bars.
      let width = toFloat(styles.width),
          height = toFloat(styles.height);
  
      // Width & height include paddings and borders when the 'border-box' box
      // model is applied (except for IE).
      if (styles.boxSizing === 'border-box') {
          // Following conditions are required to handle Internet Explorer which
          // doesn't include paddings and borders to computed CSS dimensions.
          //
          // We can say that if CSS dimensions + paddings are equal to the "client"
          // properties then it's either IE, and thus we don't need to subtract
          // anything, or an element merely doesn't have paddings/borders styles.
          if (Math.round(width + horizPad) !== clientWidth) {
              width -= getBordersSize(styles, 'left', 'right') + horizPad;
          }
  
          if (Math.round(height + vertPad) !== clientHeight) {
              height -= getBordersSize(styles, 'top', 'bottom') + vertPad;
          }
      }
  
      // Following steps can't be applied to the document's root element as its
      // client[Width/Height] properties represent viewport area of the window.
      // Besides, it's as well not necessary as the <html> itself neither has
      // rendered scroll bars nor it can be clipped.
      if (!isDocumentElement(target)) {
          // In some browsers (only in Firefox, actually) CSS width & height
          // include scroll bars size which can be removed at this step as scroll
          // bars are the only difference between rounded dimensions + paddings
          // and "client" properties, though that is not always true in Chrome.
          const vertScrollbar = Math.round(width + horizPad) - clientWidth;
          const horizScrollbar = Math.round(height + vertPad) - clientHeight;
  
          // Chrome has a rather weird rounding of "client" properties.
          // E.g. for an element with content width of 314.2px it sometimes gives
          // the client width of 315px and for the width of 314.7px it may give
          // 314px. And it doesn't happen all the time. So just ignore this delta
          // as a non-relevant.
          if (Math.abs(vertScrollbar) !== 1) {
              width -= vertScrollbar;
          }
  
          if (Math.abs(horizScrollbar) !== 1) {
              height -= horizScrollbar;
          }
      }
  
      return createRectInit(paddings.left, paddings.top, width, height);
  }