Bug 1174582: P2. Do not skip keyframe with negative timestamp. rpending=alfredo

dom/media/MediaFormatReader.cpp

@@ -520,7 +520,7 @@ MediaFormatReader::ShouldSkip(bool aSkipToNextKeyframe, media::TimeUnit aTimeThr
   if (NS_FAILED(rv)) {
     return aSkipToNextKeyframe;
   }
-  return nextKeyframe < aTimeThreshold;
+  return nextKeyframe < aTimeThreshold && nextKeyframe.ToMicroseconds() >= 0;
 }
 
 nsRefPtr<MediaDecoderReader::VideoDataPromise>