message: Use `tex` instead of `this.texture`
  In `update` method , there is already  `tex` , we shouldn't use `this.texture` any more.
diff: @@ -74,7 +74,7 @@ export default class TextureTransform {
  */
  update(forceUpdate)
  {
  - const tex = this.texture;
  + const tex = this._texture;
  if (!tex || !tex.valid)
  {
  @@ -82,14 +82,14 @@ export default class TextureTransform {
  }
  if (!forceUpdate
  - && this._lastTextureID === this.texture._updateID)
  + && this._lastTextureID === tex._updateID)
  {
  return;
  }
  - this._lastTextureID = this.texture._updateID;
  + this._lastTextureID = tex._updateID;
  - const uvs = this.texture._uvs;
  + const uvs = tex._uvs;
  this.mapCoord.set(uvs.x1 - uvs.x0, uvs.y1 - uvs.y0, uvs.x3 - uvs.x0, uvs.y3 - uvs.y0, uvs.x0, uvs.y0);
  