fix: make `can_hoist` undefined by default

packages/svelte/src/compiler/phases/1-parse/state/tag.js

@@ -391,7 +391,7 @@ function open(parser) {
 			parameters: function_expression.params,
 			body: create_fragment(),
 			metadata: {
-				can_hoist: false,
+				can_hoist: undefined,
 				sites: new Set()
 			}
 		});

packages/svelte/src/compiler/types/template.d.ts

@@ -463,7 +463,7 @@ export namespace AST {
 		body: Fragment;
 		/** @internal */
 		metadata: {
-			can_hoist: boolean;
+			can_hoist?: boolean;
 			/** The set of components/render tags that could render this snippet,
 			 * used for CSS pruning */
 			sites: Set<Component | SvelteComponent | SvelteSelf | RenderTag>;