do not suggest completions for empty dot target

pkg/analysis_server/test/completion_test.dart

Index: pkg/analysis_server/test/completion_test.dart
diff --git a/pkg/analysis_server/test/completion_test.dart b/pkg/analysis_server/test/completion_test.dart
index d04fa7a6d948d1e1a2e011ef20fc6bcb9edb7f16..a6c90b8199210eb5313c059b1d7e3520723e9384 100644
--- a/pkg/analysis_server/test/completion_test.dart
+++ b/pkg/analysis_server/test/completion_test.dart
@@ -644,10 +644,10 @@ class Foo {this.!1}''', <String>["1-Object"], failingTests: '1');
         }''', <String>["1+HttpResponse"]);
 
     buildTests('testCommentSnippets083', '''
-main() {(.!1)}''', <String>["1-toString"], failingTests: '1');
+main() {(.!1)}''', <String>["1-toString"]);
 
     buildTests('testCommentSnippets083a', '''
-main() { .!1 }''', <String>["1-toString"], failingTests: '1');
+main() { .!1 }''', <String>["1-toString"]);
 
     buildTests('testCommentSnippets083b', '''
 main() { null.!1 }''', <String>["1+toString"], failingTests: '1');
@@ -2011,11 +2011,9 @@ main() {
     buildTests('test020', '''var x = null.!1''', <String>["1+toString"],
         failingTests: '1');
 
-    buildTests('test021', '''var x = .!1''', <String>["1-toString"],
-        failingTests: '1');
+    buildTests('test021', '''var x = .!1''', <String>["1-toString"]);
 
-    buildTests('test022', '''var x = .!1;''', <String>["1-toString"],
-        failingTests: '1');
+    buildTests('test022', '''var x = .!1;''', <String>["1-toString"]);
 
     buildTests('test023', '''
 class Map{getKeys(){}}