function validateSrc(src, isImageCb, isVideoCb) {
  checkIsImage(src, function isAnImageUrl(isImage) {
    if (isImage) {
      isImageCb(src);
      return;
    }
    isVideoCb(src);
  });
}
Validate a texture, either as a selector or as a URL.
Detects whether `src` is pointing to an image or video and invokes the appropriate
callback.

`src` will be passed into the callback

@param {string|Element} src - URL or media element.
@param {function} isImageCb - callback if texture is an image.
@param {function} isVideoCb - callback if texture is a video.