Use appropriate props variable during invalidation

src/compiler/compile/render-dom/index.ts

@@ -80,7 +80,7 @@ export default function dom(
 			${$$props} => {
 				${uses_props && component.invalidate('$$props', `$$props = @assign(@assign({}, $$props), $$new_props)`)}
 				${writable_props.map(prop =>
-					`if ('${prop.export_name}' in $$props) ${component.invalidate(prop.name, `${prop.name} = $$props.${prop.export_name}`)};`
+					`if ('${prop.export_name}' in ${$$props}) ${component.invalidate(prop.name, `${prop.name} = ${$$props}.${prop.export_name}`)};`
 				)}
 				${component.slots.size > 0 &&
 				`if ('$$scope' in ${$$props}) ${component.invalidate('$$scope', `$$scope = ${$$props}.$$scope`)};`}