code: function Gradient(size, start) {
    this.size = size;
    this.canvas = new Canvas(1, 1);
    this.setStartPosition(start);
    this.ctx = this.canvas.getContext('2d');
    this.grad = this.ctx.createLinearGradient(
        this.from[0], this.from[1],
        this.to[0], this.to[1]);
  }
docs: Initialize a new `Gradient` node with the given `size`
  and `start` position.
  
  @param {Number} size
  @param {String} start
  @api private