 2*box_width - scroller_width + scrollbar_width,
  };

var expectedY = {
  blockStart: box_height,
  blockCenter: (3*box_height - scroller_height)/2 + scrollbar_width/2,
  blockEnd: 2*box_height - scroller_height + scrollbar_width,
};

[
  [{block: "start", inline: "start"}, expectedX.inlineStart, expectedY.blockStart],
  [{block: "start", inline: "center"}, expectedX.inlineCenter, expectedY.blockStart],
  [{block: "start", inline: "end"}, expectedX.inlineEnd, expectedY.blockStart],
  [{block: "center", inl