Fixes two jitter buffer bugs related to NACK.

Avoid decoding delta frames after a Flush() and after requesting
a key frame due to full NACK list.

BUG=
TEST=

Review URL: http://webrtc-codereview.appspot.com/247011

git-svn-id: http://webrtc.googlecode.com/svn/trunk@837 4adac7df-926f-26a2-2b94-8c16560cd09d

src/modules/video_coding/main/source/jitter_buffer.h

@@ -238,6 +238,7 @@ private:
     WebRtc_Word32           _NACKSeqNumInternal[kNackHistoryLength];
     WebRtc_UWord16          _NACKSeqNum[kNackHistoryLength];
     WebRtc_UWord32          _NACKSeqNumLength;
+    bool                    _waitingForKeyFrame;
 
     bool                    _firstPacket;
 };