Height and width is not possible to use for responsive_image element

Problem/Motivation

In the documentation for the responsive image preprocessor, you can read the following:

/**
 * Prepares variables for a responsive image.
 *
 * Default template: responsive-image.html.twig.
 *
 * @param $variables
 *   An associative array containing:
 *   - uri: The URI of the image.
 *   - width: The width of the image (if known).
 *   - height: The height of the image (if known).
 *   - attributes: Associative array of attributes to be placed in the img tag.
 *   - responsive_image_style_id: The ID of the responsive image style.
 */

The problem is that height and width is always ignored.

This is also a small performance cost, since the formatter always will provide these, which means these will have to be calculated 2 x the amount of source tags being created.

Proposed resolution

Allow use of height and weight

Remaining tasks

Do it

User interface changes

API changes

Beta phase evaluation