code: function FrameMirror(break_id, index) {
    %_Call(Mirror, this, MirrorType.FRAME_TYPE);
    this.break_id_ = break_id;
    this.index_ = index;
    this.details_ = new FrameDetails(break_id, index);
  }
docs: Mirror object for stack frames.
  @param {number} break_id The break id in the VM for which this frame is
  valid
  @param {number} index The frame index (top frame is index 0)
  @constructor
  @extends Mirror