Minecraft wiki entry for Death_messages, associated text: <player> was roasted in dragon breath
Is coded to appear when the player achieves a death that is assigned to the dragonBreath damage type.
Was added in 15w31c, appeared when the player was killed by a fireball shot by the ender dragon, but since then it has been unused, because dragon fireballs no longer deal impact damage.
See MC-84595 for more info.
<player> was roasted in dragon breath by <player/mob>
Is coded to appear when the player is hurt by a player or mob then achieves a death that is assigned to the dragonBreath damage type.
Was added later on to accompany the previous one.