TTS Pause/Resume Fails on Linux TTS-supporting Browsers

The Pause/Resume portion of the TTS component tests fail (hangs) on Linux in some browsers that are supposed to support TTS. So far we've seen the following:

• failure in Firefox 49 in the CI VMs (Fedora 24), and in desktop under Fedora 24 and openSUSE
• failure in Chrome on desktop under Fedora 24 and openSUSE

Some IRC conversation on the issue is here: https://botbot.me/freenode/fluid-work/2016-09-29/?msg=73942721&page=1

A Firefox bug report at https://bugzilla.mozilla.org/show_bug.cgi?id=1238538 seems to indicate this may be a known issue. Some testing on Firefox under Linux seems to indicate that pause/resume do not work in other contexts, such as the test page at http://eeejay.github.io/webspeechdemos/ or a quick JSFiddle at https://jsfiddle.net/5fewtbpv/7/