Fix JSExport test.

Author: ilonatommy

src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System/Runtime/InteropServices/JavaScript/JSExportTest.cs

@@ -440,14 +440,8 @@ public async Task InternalsVisibleToDoesntBreak()
         [Fact]
         public async void JSExportCompletedTaskReturnsResolvedPromise()
         {
-            try
-            {
-                await JavaScriptTestHelper.InvokeReturnCompletedTask();
-            }
-            catch (Exception ex)
-            {
-                Assert.Fail($"JSExport failed with {ex}");
-            }
+            string result = await JavaScriptTestHelper.InvokeReturnCompletedTask();
+            Assert.Equal("resolved", result);
         }
     }
 }

src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System/Runtime/InteropServices/JavaScript/JavaScriptTestHelper.cs

@@ -446,7 +446,7 @@ public static Exception EchoException([JSMarshalAs<JSType.Error>] Exception arg1
         internal static partial Task ReturnResolvedPromise();
 
         [JSImport("invokeReturnCompletedTask", "JavaScriptTestHelper")]
-        internal static partial Task InvokeReturnCompletedTask();
+        internal static partial Task<string> InvokeReturnCompletedTask();
 
         [JSExport]
         internal static Task ReturnCompletedTask()

src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System/Runtime/InteropServices/JavaScript/JavaScriptTestHelper.mjs

@@ -252,14 +252,12 @@ export function returnResolvedPromise() {
 
 export async function invokeReturnCompletedTask() {
     const JavaScriptTestHelper = dllExports.System.Runtime.InteropServices.JavaScript.Tests.JavaScriptTestHelper;
-    const p = JavaScriptTestHelper['ReturnCompletedTask'];
-    await Promise.race([p, delay(100)])
-        .then(() => {
-            console.log("Promise is resolved."); // to be removed
-        })
-        .catch(() => {
-            error("Promise is rejected or timed out waiting for resolving.");
-        });
+    const p = JavaScriptTestHelper['ReturnCompletedTask']();
+    const result = await Promise.race([
+        p.then(() => "resolved"),
+        delay(1000).then(() => "timeout")
+    ]);
+    return result;
 }
 
 export function invokeStructClassRecords(arg1) {