Bug 1197075: P1. Revert "Bug 1197051 - Don't try to decode ahead while seeking - r=jya". r=edwin

dom/media/MediaDecoderStateMachine.cpp

@@ -1710,7 +1710,7 @@ MediaDecoderStateMachine::RequestVideoData()
   bool skipToNextKeyFrame = mSentFirstFrameLoadedEvent &&
     NeedToSkipToNextKeyframe();
   int64_t currentTime = mState == DECODER_STATE_SEEKING ? 0 : GetMediaTime();
-  bool forceDecodeAhead = mSentFirstFrameLoadedEvent && !IsSeeking() &&
+  bool forceDecodeAhead = mSentFirstFrameLoadedEvent &&
     static_cast<uint32_t>(VideoQueue().GetSize()) <= SCARCE_VIDEO_QUEUE_SIZE;
 
   SAMPLE_LOG("Queueing video task - queued=%i, decoder-queued=%o, skip=%i, time=%lld",