fix: loosen input in button error (#10083)

The validation exists to error on html that would result in the browser repairing it, causing hydration errors. input is never moved, so we can remove it from the array

---------

Co-authored-by: Simon H <5968653+dummdidumm@users.noreply.github.com>

Author: trueadm

.changeset/good-cars-visit.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: allow input elements within button elements

packages/svelte/src/compiler/phases/1-parse/utils/html.js

@@ -121,15 +121,8 @@ function validate_code(code) {
 
 // based on http://developers.whatwg.org/syntax.html#syntax-tag-omission
 
-const interactive_elements = new Set([
-	'a',
-	'button',
-	'iframe',
-	'embed',
-	'input',
-	'select',
-	'textarea'
-]);
+// while `input` is also an interactive element, it is never moved by the browser, so we don't need to check for it
+const interactive_elements = new Set(['a', 'button', 'iframe', 'embed', 'select', 'textarea']);
 
 /** @type {Record<string, Set<string>>} */
 const disallowed_contents = {