function processColors(colors, className)
            {
                for (var color of colors) {
                    var child = this._decorationsElement.createChild("div", className);
                    this._decorationsElement.classList.remove("hidden");
                    child.style.backgroundColor = color;
                    child.style.borderColor = color;
                    if (offset)
                        child.style.marginLeft = offset + "px";
                    offset += 3;
                }
            }
@param {!Set<string>} colors
@param {string} className
@this {WebInspector.ElementsTreeElement}