function getRefs(fileInfo, offset) {
    var request = buildRequest(fileInfo, "refs", offset);
    try {
        ternServer.request(request, function (error, data) {
            if (error) {
                _log("Error returned from Tern 'refs' request: " + error);
                var response = {
                    type: MessageIds.TERN_REFS,
                    error: error.message
                };
                self.postMessage(response);
                return;
            }
            var response = {
                type: MessageIds.TERN_REFS,
                file: fileInfo.name,
                offset: offset,
                references: data
            };
            // Post a message back to the main thread with the results
            self.postMessage(response);
        });
    } catch (e) {
        _reportError(e, fileInfo.name);
    }
}
Get all References location
@param {{type: string, name: string, offsetLines: number, text: string}} fileInfo
- type of update, name of file, and the text of the update.
For "full" updates, the whole text of the file is present. For "part" updates,
the changed portion of the text. For "empty" updates, the file has not been modified
and the text is empty.
@param {{line: number, ch: number}} offset - the offset into the
file for cursor