add test

test/runtime/samples/dev-warning-unknown-props-2/Foo.svelte

@@ -0,0 +1 @@
+Foo

test/runtime/samples/dev-warning-unknown-props-2/_config.js

@@ -0,0 +1,9 @@
+export default {
+	compileOptions: {
+		dev: true
+	},
+
+	warnings: [
+		`<Foo> was created with unknown prop 'fo'`
+	]
+};

test/runtime/samples/dev-warning-unknown-props-2/main.svelte

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