treat `slot` the same as other props - closes #9455 (#9457)

Co-authored-by: Rich Harris <rich.harris@vercel.com>

.changeset/tiny-kings-whisper.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: treat `slot` the same as other props

packages/svelte/src/compiler/phases/3-transform/client/visitors/template.js

@@ -710,7 +710,6 @@ function serialize_inline_component(node, component_name, context) {
 		} else if (attribute.type === 'SpreadAttribute') {
 			props_and_spreads.push(/** @type {import('estree').Expression} */ (context.visit(attribute)));
 		} else if (attribute.type === 'Attribute') {
-			if (attribute.name === 'slot') continue;
 			if (attribute.name.startsWith('--')) {
 				custom_css_props.push(
 					b.init(attribute.name, serialize_attribute_value(attribute.value, context)[1])

packages/svelte/src/compiler/phases/3-transform/server/transform-server.js

@@ -782,7 +782,6 @@ function serialize_inline_component(node, component_name, context) {
 		} else if (attribute.type === 'SpreadAttribute') {
 			props_and_spreads.push(/** @type {import('estree').Expression} */ (context.visit(attribute)));
 		} else if (attribute.type === 'Attribute') {
-			if (attribute.name === 'slot') continue;
 			if (attribute.name.startsWith('--')) {
 				const value = serialize_attribute_value(attribute.value, context, false, true);
 				custom_css_props.push(b.init(attribute.name, value));