function TileImagery(imagery, textureCoordinateRectangle, useWebMercatorT) {
  this.readyImagery = undefined;
  this.loadingImagery = imagery;
  this.textureCoordinateRectangle = textureCoordinateRectangle;
  this.textureTranslationAndScale = undefined;
  this.useWebMercatorT = useWebMercatorT;
}
The assocation between a terrain tile and an imagery tile.

@alias TileImagery
@private

@param {Imagery} imagery The imagery tile.
@param {Cartesian4} textureCoordinateRectangle The texture rectangle of the tile that is covered
       by the imagery, where X=west, Y=south, Z=east, W=north.
@param {boolean} useWebMercatorT true to use the Web Mercator texture coordinates for this imagery tile.