paper-dropdown double-click causes Uncaught TypeError: Cannot read property 'position' of null

[jodekirk]

Double-clicking on the paper-dropdown causes an error:
Uncaught TypeError: Cannot read property 'position' of null
In the first if statement here:

resetTargetDimensions: function() {
var dims = this.dimensions;
var style = this.target.style;
if (dims.position.h_by === this.localName) {
style[dims.position.h] = null;
dims.position.h_by = null;
}
if (dims.position.v_by === this.localName) {
style[dims.position.v] = null;
dims.position.v_by = null;
}

  var style = this.sizingTarget.style;
  style.width = null;
  style.height = null;
  this.super();
},