Receiver code used to indicate a flush error even if the incoming packet is a keyframe, forcing a request of a keyframe. Now it takes this keyframe into account and doesn't error as the stream is decodable from this point. BUG= R=stefan@webrtc.org Review URL: https://webrtc-codereview.appspot.com/15549005 git-svn-id: http://webrtc.googlecode.com/svn/trunk@6188 4adac7df-926f-26a2-2b94-8c16560cd09d