use $$props directly in runes mode

Author: Rich-Harris

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

@@ -73,9 +73,8 @@ export function serialize_get_binding(node, state) {
 		}
 
 		if (
-			state.analysis.runes &&
 			!state.analysis.accessors &&
-			!binding.reassigned &&
+			!(state.analysis.runes ? binding.reassigned : binding.mutated) &&
 			!binding.initial
 		) {
 			return b.member(b.id('$$props'), node);

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

@@ -67,17 +67,24 @@ export const javascript_visitors_legacy = {
 					state.scope.get(declarator.id.name)
 				);
 
-				declarations.push(
-					b.declarator(
-						declarator.id,
-						get_props_method(
-							binding,
-							state,
-							binding.prop_alias ?? declarator.id.name,
-							declarator.init && /** @type {import('estree').Expression} */ (visit(declarator.init))
+				if (
+					state.analysis.accessors ||
+					(state.analysis.immutable ? binding.reassigned : binding.mutated) ||
+					declarator.init
+				) {
+					declarations.push(
+						b.declarator(
+							declarator.id,
+							get_props_method(
+								binding,
+								state,
+								binding.prop_alias ?? declarator.id.name,
+								declarator.init &&
+									/** @type {import('estree').Expression} */ (visit(declarator.init))
+							)
 						)
-					)
-				);
+					);
+				}
 
 				continue;
 			}