Fix empty response on certain Apache/PHP versions.

I ran into this on an shared hosting somewhere with
5.3.17 on Apache 2.

The server response on the POST ajax request is empty.

Echoing an non-empty string anywhere fixes the problem.

Bug: 45338
Change-Id: I8c4182d3e879cff84db48ea7c1b0ab2e51d5f02c