svelte registr SSR support MJS es6 modules inside svelte file

test/server-side-rendering/index.js

@@ -58,8 +58,14 @@ describe("ssr", () => {
 				generate: 'ssr',
 				format: 'cjs'
 			};
+			
+			function es6Compiler(code) {
+				return require("@babel/core").transformSync(code, {
+					plugins: ["@babel/plugin-transform-modules-commonjs"],
+				});
+			}
 
-			require("../../register")(compileOptions);
+			require("../../register")(compileOptions,es6Compiler);
 
 			try {
 				const Component = require(`${dir}/main.svelte`).default;

test/server-side-rendering/samples/component-import-mjs/Widget.mjs

@@ -0,0 +1,2 @@
+import Widget from "./Widget.svelte";
+export default Widget;

test/server-side-rendering/samples/component-import-mjs/Widget.svelte

@@ -0,0 +1,4 @@
+<script>
+</script>
+
+<div>The Widget</div>

test/server-side-rendering/samples/component-import-mjs/_expected.html

@@ -0,0 +1 @@
+<div>The Widget</div>

test/server-side-rendering/samples/component-import-mjs/main.svelte

@@ -0,0 +1,5 @@
+<script>
+  import Widget from "./Widget.mjs";
+</script>
+
+<Widget />