Remove unused analysisContext from completion request and contributors

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

Index: pkg/analysis_server/test/services/completion/dart/type_member_contributor_test.dart
diff --git a/pkg/analysis_server/test/services/completion/dart/type_member_contributor_test.dart b/pkg/analysis_server/test/services/completion/dart/type_member_contributor_test.dart
index 74f0de869e625e8406471c33dff1165f5b676c5c..6c8b6157a7c356698b9308374a06fbf20b9235ae 100644
--- a/pkg/analysis_server/test/services/completion/dart/type_member_contributor_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/type_member_contributor_test.dart
@@ -60,6 +60,8 @@ void f(Derived d) {
     // SimpleIdentifier  PrefixedIdentifier  ExpressionStatement
     addTestSource('const g = "hello"; f() {g.^ int y = 0;}');
     await computeSuggestions();
+    assertSuggestMethod('toString', 'Object', 'String');
+    // fails this assertion because type of const is not properly inferred
     assertSuggestGetter('length', 'int');
   }