Death Counter Scoreboard
It is not possible to track how many times a player has died in Minecraft 1.8, but now you have the chance to utilize the mod called Death Counter Scoreboard, featured here, to change that!

This behavior pack is entirely crafted using functions from Minecraft Bedrock and allows you to set up a scoreboard that will start tracking the number of player deaths in your world, making it perfect for mini-game development, as well as being a fun addition to your survival Minecraft world.