remove duplicate suggestions

pkg/analysis_server/test/domain_completion_test.dart

Index: pkg/analysis_server/test/domain_completion_test.dart
diff --git a/pkg/analysis_server/test/domain_completion_test.dart b/pkg/analysis_server/test/domain_completion_test.dart
index a88966bca1d0e8a43ddfce13b18579a3a7083c57..d283928b66798e20425d963dbd9e87004dea19e9 100644
--- a/pkg/analysis_server/test/domain_completion_test.dart
+++ b/pkg/analysis_server/test/domain_completion_test.dart
@@ -46,10 +46,20 @@ class CompletionTest extends AbstractAnalysisTest {
   void assertHasResult(CompletionSuggestionKind kind, String completion,
       [CompletionRelevance relevance = CompletionRelevance.DEFAULT,
       bool isDeprecated = false, bool isPotential = false]) {
-    var cs = suggestions.firstWhere((cs) => cs.completion == completion, orElse: () {
+    var cs;
+    suggestions.forEach((s) {
+      if (s.completion == completion) {
+        if (cs == null) {
+          cs = s;
+        } else {
+          fail('expected exactly one $completion but found > 1');
+        }
+      }
+    });
+    if (cs == null) {
       var completions = suggestions.map((s) => s.completion).toList();
       fail('expected "$completion" but found\n $completions');
-    });
+    }
     expect(cs.kind, equals(kind));
     expect(cs.relevance, equals(relevance));
     expect(cs.selectionOffset, equals(completion.length));
@@ -98,6 +108,7 @@ class CompletionTest extends AbstractAnalysisTest {
         replacementLength = notification.getParameter(REPLACEMENT_LENGTH);
         suggestionsDone = notification.getParameter(LAST);
         expect(suggestionsDone, isNotNull);
+        suggestions = [];
         for (Map<String, Object> json in notification.getParameter(RESULTS)) {
           expect(json, isNotNull);
           suggestions.add(new CompletionSuggestion.fromJson(json));