Fix lint error due to private variable
Fix lint error due to private variable

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