support POST responses for html

[jeffkaufman]

Reported on the mailing list:

I am using pagespeed with proxy_pass directive:

location ~* ^/path/ {
    proxy_pass http://host;
    proxy_cache off;
    proxy_cache_valid 0;
    pagespeed on;
}

Responses to GET requests are being transformed normally but responses for POST queries are totally ignored by Pagespeed.
WTF? Content-Type of response is text/html in both cases.

Testing on jefftk.com, I could reproduce this.

Next step is to run pagespeed locally and figure out where nginx processing of POSTs diverges from GETs.

[oschaaf]

Fixed in trunk-tracking via #767 (8f6bb0c)