Function isModifierKey

static/libs/codemirror.js:6723–6726

(value)

// Modifier key presses don't count as 'real' key presses for the
// purpose of keymap fallthrough.
function isModifierKey(value) {
  var name = typeof value == "string" ? value : keyNames[value.keyCode];
  return name == "Ctrl" || name == "Alt" || name == "Shift" || name == "Mod"
}

function addModifierNames(name, event, noShift) {
  var base = name;