get displayName()
    {
        if (this._displayName)
            return this._displayName;

        if (this.isDataURL())
            return this.dataURLDisplayName();
        if (this.isAboutBlank())
            return this.url;

        this._displayName = this.lastPathComponent;
        if (!this._displayName)
            this._displayName = (this.host || "") + "/";
        if (this._displayName === "/")
            this._displayName = this.url;
        return this._displayName;
    }
@param {string} baseURL
@param {string} href
@return {?string}