disable warning unknown_props if uses $$rest

src/compiler/compile/render_dom/index.ts

@@ -393,7 +393,7 @@ export default function dom(
 		});
 
 		let unknown_props_check;
-		if (component.compile_options.dev && !component.var_lookup.has('$$props')) {
+		if (component.compile_options.dev && !(uses_props || uses_rest)) {
 			unknown_props_check = b`
 				const writable_props = [${writable_props.map(prop => x`'${prop.export_name}'`)}];
 				@_Object.keys($$props).forEach(key => {

test/runtime/samples/dev-warning-unknown-props-with-$$props/Foo.svelte

@@ -4,4 +4,4 @@
 </script>
 
 <div>{foo}</div>
-<div>{JSON.stringify($$props)}</div>
+<div>{JSON.stringify($$rest)}</div>

test/runtime/samples/dev-warning-unknown-props-with-$$rest/Foo.svelte

@@ -0,0 +1,7 @@
+<script>
+	export let foo = undefined;
+
+</script>
+
+<div>{foo}</div>
+<div>{JSON.stringify($$props)}</div>

test/runtime/samples/dev-warning-unknown-props-with-$$rest/_config.js

@@ -0,0 +1,7 @@
+export default {
+	compileOptions: {
+		dev: true
+	},
+
+	warnings: []
+};

test/runtime/samples/dev-warning-unknown-props-with-$$rest/main.svelte

@@ -0,0 +1,5 @@
+<script>
+	import Foo from './Foo.svelte';
+</script>
+
+<Foo fo="sho"/>