Correction to check if rtx is enabled on send-side (and not receive) when updating rtx send bitrate stat. Remove unneeded guarded by annotations. BUG= R=mflodman@webrtc.org, stefan@webrtc.org Review URL: https://webrtc-codereview.appspot.com/41729004 Cr-Commit-Position: refs/heads/master@{#8239} git-svn-id: http://webrtc.googlecode.com/svn/trunk@8239 4adac7df-926f-26a2-2b94-8c16560cd09d