fix: virtual references remained (#259)

Author: ota-meshi

src/context/script-let.ts

@@ -516,7 +516,6 @@ export class ScriptLetContext {
           callback!(fn.params, result);
           for (let index = 0; index < fn.params.length; index++) {
             const p = fn.params[index];
-            (p as any).parent = parents![index];
             if (this.ctx.isTypeScript()) {
               const typeAnnotation = (p as any).typeAnnotation;
               delete (p as any).typeAnnotation;
@@ -529,6 +528,7 @@ export class ScriptLetContext {
 
               removeAllScopeAndVariableAndReference(typeAnnotation, result);
             }
+            (p as any).parent = parents![index];
           }
 
           // Process for scope

tests/fixtures/parser/ast/issue325-eslint-plugin-svelte-input.svelte

@@ -0,0 +1,18 @@
+<script lang="ts">
+    export let message: string|undefined;
+    export const formatMessage = async (message: string): Promise<string> => {
+        return new Promise(resolve => {
+        resolve(message);
+        });
+    };
+</script>
+
+{#if !message}
+    No message
+{:else}
+    {#await formatMessage(message)}
+        Loading...
+    {:then result}
+        {result}
+    {/await}
+{/if}