[dds/dap] Fix a bug that could result in test failures

This logic was inverted and could result in duplicate terminate requests being sent. Depending on timing, this request might be sent but not responded to (because the DA was already shutting down), causing a "Application terminated with pending terminate request" error.

Change-Id: If89f002792878f8a5ce12341536be70ee01cde11
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/310380
Commit-Queue: Ben Konyi <[email protected]>
Reviewed-by: Ben Konyi <[email protected]>

Author: DanTup

pkg/dds/test/dap/integration/dart_test_test.dart

@@ -136,7 +136,7 @@ main() {
         cwd: dap.testAppDir.path,
       );
 
-      // Send a single terinate, and expect a clean exit (with a `terminated`
+      // Send a single terminate, and expect a clean exit (with a `terminated`
       // event).
       await Future.wait([
         dap.client.event('terminated'),

pkg/dds/test/dap/integration/test_support.dart

@@ -233,7 +233,7 @@ environment:
 
   Future<void> tearDown() async {
     // If the test hasn't already sent terminate, do that before shutting down.
-    if (client.hasSentTerminateRequest) {
+    if (!client.hasSentTerminateRequest) {
       await client.terminate();
     }
     await client.stop();