fix combinator contributor

pkg/analysis_server/test/services/completion/dart/completion_contributor_util.dart

Index: pkg/analysis_server/test/services/completion/dart/completion_contributor_util.dart
diff --git a/pkg/analysis_server/test/services/completion/dart/completion_contributor_util.dart b/pkg/analysis_server/test/services/completion/dart/completion_contributor_util.dart
index 9b200d9189eeda3e2c7a69ce613e1a0801289533..c08a073a107ea348ce4353799b1adde6ac160344 100644
--- a/pkg/analysis_server/test/services/completion/dart/completion_contributor_util.dart
+++ b/pkg/analysis_server/test/services/completion/dart/completion_contributor_util.dart
@@ -215,9 +215,9 @@ abstract class DartCompletionContributorTest extends AbstractContextTest {
   }
 
   CompletionSuggestion assertSuggestTopLevelVar(String name, String returnType,
-      [int relevance = DART_RELEVANCE_DEFAULT,
-      CompletionSuggestionKind kind = CompletionSuggestionKind.INVOCATION,
-      String importUri]) {
+      {int relevance: DART_RELEVANCE_DEFAULT,
+      CompletionSuggestionKind kind: CompletionSuggestionKind.INVOCATION,
+      String importUri}) {
     CompletionSuggestion cs = assertSuggest(name,
         csKind: kind, relevance: relevance, importUri: importUri);
     expect(cs.returnType, returnType != null ? returnType : 'dynamic');