globalOffsetsToRelativeOffsets({ start, end }) {
        return domManager.globalOffsetsToRelativeOffsets(start, end);
      }
Converts global offsets to relative offsets.

@param {Object} start - The start global offset in codepoints.
@param {Object} end - The end global offset in codepoints.
@returns {undefined|{start: string, startOffset: number, end: string, endOffset: number}} - The relative offsets.