fix: don't use Math.floor in DomRenderer charWidth computation
fix: don't use Math.floor in DomRenderer charWidth computation

Fixes #2063

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