> > I checked again on browser compatibility:
> > 
> > el6: firefox 38 - ok, google-chrome 27 - no
>
> It looks like this does mean that people using RHEL6 won't have the option of chrome - can they update chrome?
>

It turns out that google-chrome 38 is available for RHEL6/SL6 via an old chromium build. Promises are supported (passes my tests).

See here:
http://www.if-not-true-then-false.com/2013/install-chromium-on-centos-red-hat-rhel

This is where I got the working chromium 38 (no explanation of why there are no newer builds)
http://people.centos.org/hughesjr/chromium/6/x86_64/RPMS/

There appear to be newer builds here: (but I will not test them)
http://install.linux.ncsu.edu/pub/yum/itecs/public/chromium-dev/rhel6/x86_64/

My SL6 google-chrome and chromium instructions:
https://www.triumf.info/wiki/DAQwiki/index.php/SLinstall#Install_Google_Chrome_web_browser_.2864-bit_SL6.29

K.O.