Add backgroundPosition to VALID STYLES.

Roll back previous fix, and explicitly set backgroundRepeat to "repeat", because it seems as if it's being overwritten by merging styles (undefined values are stripped)

packages/block-editor/src/components/global-styles/background-panel.js

@@ -346,15 +346,7 @@ function BackgroundSizeToolsPanelItem( {
 		inheritedValue?.background?.backgroundSize;
 	const repeatValue =
 		style?.background?.backgroundRepeat ||
-		/*
-		 * Edge case where theme.json has a backgroundSize value of 'cover'
-		 * and a backgroundRepeat value. If a user backgroundSize is set,
-		 * ignore the inherited backgroundRepeat value as style?.background?.backgroundRepeat
-		 * is deliberately set to undefined in updateBackgroundSize().
-		 */
-		( !! style?.background?.backgroundSize
-			? undefined
-			: inheritedValue?.background?.backgroundRepeat );
+		inheritedValue?.background?.backgroundRepeat;
 	const imageValue =
 		style?.background?.backgroundImage?.url ||
 		inheritedValue?.background?.backgroundImage?.url;
@@ -447,7 +439,7 @@ function BackgroundSizeToolsPanelItem( {
 			setImmutably(
 				style,
 				[ 'background', 'backgroundRepeat' ],
-				repeatCheckedValue === true ? 'no-repeat' : undefined
+				repeatCheckedValue === true ? 'no-repeat' : 'repeat'
 			)
 		);
 

packages/blocks/src/api/constants.js

@@ -44,13 +44,18 @@ export const __EXPERIMENTAL_STYLE_PROPERTY = {
 	backgroundRepeat: {
 		value: [ 'background', 'backgroundRepeat' ],
 		support: [ 'background', 'backgroundRepeat' ],
-		useEngine: true,
+		useEngine: false,
 	},
 	backgroundSize: {
 		value: [ 'background', 'backgroundSize' ],
 		support: [ 'background', 'backgroundSize' ],
 		useEngine: true,
 	},
+	backgroundPosition: {
+		value: [ 'background', 'backgroundPosition' ],
+		support: [ 'background', 'backgroundPosition' ],
+		useEngine: true,
+	},
 	borderColor: {
 		value: [ 'border', 'color' ],
 		support: [ '__experimentalBorder', 'color' ],