$ sudo apt-get update
$ sudo apt-get install icedtea-8-plugin 

icedtea-8-plugin is installed in your system.

Make ensure the icedtea-8-plugin package were installed using the commands given below,

$ sudo dpkg-query -l | grep icedtea-8-plugin *

You will get with icedtea-8-plugin package name, version, architecture and description in a table

icedtea-8-plugin package basic information: