background-size auto is the same as no background-size

bad rebase

docs/reference-guides/block-api/block-supports.md

@@ -149,13 +149,13 @@ When a background image is selected, the image data is stored in the `style.back
 When a background images is selected and its position or size are changed, the background-position is stored in the `style.background.backgroundPosition` and its background-size in `style.background.backgroundSize` attribute.
 
 -   `style`: an attribute of `object` type with no default assigned. This is added when `backgroundImage` or `backgroundSize` support is declared. It stores the custom values set by the user.
-    -   `background`: an attribute of `object` type.
-        - `backgroundImage`: an attribute of `object` type, containing information about the selected image
+    -   `background`: an attribute of `object` type. 
+        - `backgroundImage`: an attribute of `object` type, containing information about the selected image 
             - `url`: type `string`, URL to the image
             - `id`: type `int`, media attachment ID
             - `source`: type `string`, at the moment the only value is `file`
-            - `title`: type `string`, title of the media attachment
-        - `backgroundPosition`: an attribute of `string` type, defining the background images position, selected by FocalPointPicker and used in CSS as the [`background-position`](https://developer.mozilla.org/en-US/docs/Web/CSS/background-position) value.
+            - `title`: type `string`, title of the media attachment 
+        - `backgroundPosition`: an attribute of `string` type, defining the background images position, selected by FocalPointPicker and used in CSS as the [`background-position`](https://developer.mozilla.org/en-US/docs/Web/CSS/background-position) value. 
         - `backgroundSize`: an attribute of `string` type. defining the CSS [`background-size`](https://developer.mozilla.org/en-US/docs/Web/CSS/background-size) value.
 
 The block can apply a default background image, position and size by specifying its own attribute with a default. For example:
@@ -484,10 +484,10 @@ When the block declares support for `color.link`, the attributes definition is e
                         color: {
                             text: 'var:preset|color|contrast',
                         },
-						":hover": {
-							color: {
-								text: "#000000"
-							}
+						":hover": { 
+							color: { 
+								text: "#000000" 
+							} 
 						}
                     }
                 }

lib/block-supports/background.php

@@ -39,8 +39,6 @@ function gutenberg_register_background_support( $block_type ) {
  * @return array                     Style engine array of CSS string and style declarations.
  */
 function gutenberg_get_background_support_styles( $background_styles = array() ) {
-	$background_styles['backgroundSize'] = ! empty( $background_styles['backgroundSize'] ) ? $background_styles['backgroundSize'] : 'auto';
-
 	return gutenberg_style_engine_get_styles( array( 'background' => $background_styles ) );
 }
 

packages/block-editor/src/hooks/background.js

@@ -641,3 +641,9 @@ export function BackgroundImagePanel( props ) {
 		</InspectorControls>
 	);
 }
+
+export default {
+	useBlockProps,
+	attributeKeys: [ 'style' ],
+	hasSupport: hasBackgroundSupport,
+};

packages/block-editor/src/hooks/index.js

@@ -48,6 +48,7 @@ createBlockEditFilter(
 );
 createBlockListBlockFilter( [
 	align,
+	background,
 	style,
 	color,
 	dimensions,

phpunit/block-supports/background-test.php

@@ -242,13 +242,13 @@ public function data_get_background_support_styles() {
 						'source' => 'file',
 					),
 				),
-				'expected_css'     => "background-image:url('https://example.com/image.jpg');background-size:auto;",
+				'expected_css'     => "background-image:url('https://example.com/image.jpg');",
 			),
 			'css generated where backgroundImage is a string' => array(
 				'background_style' => array(
 					'backgroundImage' => "url('https://example.com/image.jpg')",
 				),
-				'expected_css'     => "background-image:url('https://example.com/image.jpg');background-size:auto;",
+				'expected_css'     => "background-image:url('https://example.com/image.jpg');",
 			),
 			'css generated with escaped URL'         => array(
 				'background_style' => array(