Make Analysis Server tests use MockSdk again.

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

Index: pkg/analysis_server/test/services/completion/dart/optype_test.dart
diff --git a/pkg/analysis_server/test/services/completion/dart/optype_test.dart b/pkg/analysis_server/test/services/completion/dart/optype_test.dart
index 5c4a758dbdbc2ddc1cca2a525e857734b234ed32..f2851739bc30721e1cfb53c8bca0e629e6d0e8b0 100644
--- a/pkg/analysis_server/test/services/completion/dart/optype_test.dart
+++ b/pkg/analysis_server/test/services/completion/dart/optype_test.dart
@@ -85,11 +85,6 @@ class OpTypeTest {
     processRequiredPlugins();
   }
 
-  test_Block_final_final2() {
-    addTestSource('main() {final S^ final S x;}');
-    assertOpType(typeNames: true);
-  }
-
   test_Annotation() {
     // SimpleIdentifier  Annotation  MethodDeclaration  ClassDeclaration
     addTestSource('class C { @A^ }');
@@ -330,6 +325,11 @@ class OpTypeTest {
     assertOpType(typeNames: true);
   }
 
+  test_Block_final_final2() {
+    addTestSource('main() {final S^ final S x;}');
+    assertOpType(typeNames: true);
+  }
+
   test_Block_identifier_partial() {
     addTestSource('class X {a() {var f; {var x;} D^ var r;} void b() { }}');
     assertOpType(returnValue: true, typeNames: true, voidReturn: true);
@@ -1567,9 +1567,6 @@ class _TestSource implements Source {
   bool get isInSystemLibrary => false;
 
   @override
-  Source get librarySource => null;
-
-  @override
   String get shortName => fullName;
 
   @override