function appendLineNumber(lineNumber)
        {
            var numberString = lineNumber !== null ? numberToStringWithSpacesPadding(lineNumber + 1, 4) : spacesPadding(4);
            var lineNumberSpan = createElement("span");
            lineNumberSpan.classList.add("webkit-line-number");
            lineNumberSpan.textContent = numberString;
            child.listItemElement.appendChild(lineNumberSpan);
        }
@param {?number} baseLineNumber
@param {?number} newLineNumber
@param {string} lineContent
@param {string} changeType