Indicate non-passive scroll events for viewport
Indicate non-passive scroll events for viewport

Fixes #3004

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