generate valid code when spreading literal into props (#3185)

src/compiler/compile/render_dom/wrappers/InlineComponent/index.ts

@@ -220,9 +220,9 @@ export default class InlineComponentWrapper extends Wrapper {
 				const conditions = Array.from(all_dependencies).map(dep => `changed.${dep}`).join(' || ');
 
 				updates.push(deindent`
-					var ${name_changes} = ${all_dependencies.size === 1 ? `${conditions}` : `(${conditions})`} ? @get_spread_update(${levels}, [
+					var ${name_changes} = ${conditions ? `(${conditions}) ? @get_spread_update(${levels}, [
 						${changes.join(',\n')}
-					]) : {};
+					]) : {}` : '{}'};
 				`);
 			} else {
 				this.node.attributes

test/runtime/samples/spread-component-literal/Widget.svelte

@@ -0,0 +1,5 @@
+<script>
+	export let foo;
+</script>
+
+<p>foo: {foo}</p>

test/runtime/samples/spread-component-literal/_config.js

@@ -0,0 +1,5 @@
+export default {
+	html: `
+		<div><p>foo: bar</p></div>
+	`
+};

test/runtime/samples/spread-component-literal/main.svelte

@@ -0,0 +1,7 @@
+<script>
+	import Widget from './Widget.svelte';
+</script>
+
+<div>
+	<Widget {...{ foo: 'bar' }}/>
+</div>