Improve import prefix search results UI.

pkg/analysis_server/test/search/element_references_test.dart

Index: pkg/analysis_server/test/search/element_references_test.dart
diff --git a/pkg/analysis_server/test/search/element_references_test.dart b/pkg/analysis_server/test/search/element_references_test.dart
index f5c3f15c19b8bff97972007ab461ff9761fb86ff..8c67fc9555d333ebba71378ab01756b9e25254ff 100644
--- a/pkg/analysis_server/test/search/element_references_test.dart
+++ b/pkg/analysis_server/test/search/element_references_test.dart
@@ -297,25 +297,6 @@ main(A a, B b, C c) {
     });
   }
 
-  test_prefix() {
-    addTestFile('''
-import 'dart:async' as ppp;
-main() {
-  ppp.Future a;
-  ppp.Stream b;
-}
-''');
-    return findElementReferences("ppp;", false).then((_) {
-      expect(searchElement.kind, ElementKind.PREFIX);
-      expect(searchElement.name, 'ppp');
-      expect(searchElement.location.startLine, 1);
-      expect(results, hasLength(3));
-      assertHasResult(SearchResultKind.DECLARATION, 'ppp;');
-      assertHasResult(SearchResultKind.REFERENCE, 'ppp.Future');
-      assertHasResult(SearchResultKind.REFERENCE, 'ppp.Stream');
-    });
-  }
-
   test_label() {
     addTestFile('''
 main() {
@@ -635,6 +616,38 @@ globalFunction(Base b) {
     });
   }
 
+  test_prefix() {
+    addTestFile('''
+import 'dart:async' as ppp;
+main() {
+  ppp.Future a;
+  ppp.Stream b;
+}
+''');
+    return findElementReferences("ppp;", false).then((_) {
+      expect(searchElement.kind, ElementKind.PREFIX);
+      expect(searchElement.name, 'ppp');
+      expect(searchElement.location.startLine, 1);
+      expect(results, hasLength(3));
+      assertHasResult(SearchResultKind.DECLARATION, 'ppp;');
+      assertHasResult(SearchResultKind.REFERENCE, 'ppp.Future');
+      assertHasResult(SearchResultKind.REFERENCE, 'ppp.Stream');
+    });
+  }
+
+  test_prefix_null() {
+    addTestFile('''
+import 'dart:async';
+main() {
+  Future a;
+  Stream b;
+}
+''');
+    return findElementReferences("import ", false).then((_) {
+      expect(searchElement, isNull);
+    });
+  }
+
   test_topLevelVariable_explicit() {
     addTestFile('''
 var vvv = 1;