Make tests use buffer API over _core
Make tests use buffer API over _core

Tyriar/xterm.js,xtermjs/xterm.js,sourcelair/xterm.js,Tyriar/xterm.js,sourcelair/xterm.js,sourcelair/xterm.js,Tyriar/xterm.js,xtermjs/xterm.js,xtermjs/xterm.js,xtermjs/xterm.js,Tyriar/xterm.js,Tyriar/xterm.js,xtermjs/xterm.js,sourcelair/xterm.js