Macro. Remove @SkippedTest() for a test that actually passes.

Change-Id: I23f38f9bc3c0b3fcc81387af4e7d4f6037e7e89c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/349200
Reviewed-by: Brian Wilkerson <[email protected]>
Reviewed-by: Phil Quitslund <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>

Author: scheglov

pkg/analyzer/test/src/summary/macro_test.dart

@@ -926,7 +926,6 @@ class MacroArgumentsTest extends MacroElementsBaseTest {
   @override
   bool get keepLinkingLibraries => true;
 
-  @SkippedTest(reason: 'Fails') // TODO(scheglov): triage.
   test_error() async {
     await _assertTypesPhaseArgumentsText(
       fields: {