function createEmptyUpdate(path) {
    return {type: MessageIds.TERN_FILE_INFO_TYPE_EMPTY,
        name: path,
        offsetLines: 0,
        text: ""};
}
Create a "empty" update object.

@param {string} path - full path of the file.
@return {{type: string, name: string, offsetLines: number, text: string}} -
"empty" update.