Consider this code:

final List colors = new List(3);

main() {
  for (var i = 0; i < colors.length; i++) {
    print(colors[i]);
  }
}

dart2js generates this:

$.main = function() {
  var i;
  for (var i = 0; i < $.get$length$as($.get$colors()); ++i)
    $.Primitives_printString($.toString$0($.$index$as($.get$colors(), i)));
};

Could it know the length of colors at compile time, and inline the number 3 ?