fix: prune typescript class field declarations (#16154)

* fix: prune typescript class field declarations

* add test

.changeset/neat-lemons-occur.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: prune typescript class field declarations

packages/svelte/src/compiler/phases/1-parse/remove_typescript_nodes.js

@@ -115,6 +115,19 @@ const visitors = {
 	TSDeclareFunction() {
 		return b.empty;
 	},
+	ClassBody(node, context) {
+		const body = [];
+		for (const _child of node.body) {
+			const child = context.visit(_child);
+			if (child.type !== 'PropertyDefinition' || !child.declare) {
+				body.push(child);
+			}
+		}
+		return {
+			...node,
+			body
+		};
+	},
 	ClassDeclaration(node, context) {
 		if (node.declare) {
 			return b.empty;

packages/svelte/tests/runtime-runes/samples/typescript/main.svelte

@@ -14,6 +14,7 @@
 
 	class Foo<T> {
 		public name: string;
+		declare bar: string;
 		x = 'x' as const;
 		constructor(name: string) {
 			this.name = name;