function PostProcessStageTextureCache(postProcessStageCollection) {
  this._collection = postProcessStageCollection;

  this._framebuffers = [];
  this._stageNameToFramebuffer = {};

  this._width = undefined;
  this._height = undefined;
  this._updateDependencies = false;
}
Creates a minimal amount of textures and framebuffers.

@alias PostProcessStageTextureCache
@constructor

@param {PostProcessStageCollection} postProcessStageCollection The post process collection.

@private