GenerateHintsTask - partial implementation.

pkg/analyzer/test/src/mock_sdk.dart

Index: pkg/analyzer/test/src/mock_sdk.dart
diff --git a/pkg/analyzer/test/src/mock_sdk.dart b/pkg/analyzer/test/src/mock_sdk.dart
index 67168012e64f59dea9ef0f93a828342a280eb46b..7cadfcc5b7db566df235908c22cd80f1a5a8a634 100644
--- a/pkg/analyzer/test/src/mock_sdk.dart
+++ b/pkg/analyzer/test/src/mock_sdk.dart
@@ -98,6 +98,11 @@ abstract class Map<K, V> extends Object {
 external bool identical(Object a, Object b);
 
 void print(Object object) {}
+
+class _Override {
+  const _Override();
+}
+const Object override = const _Override();
 ''');
 
   static const _MockSdkLibrary LIB_ASYNC = const _MockSdkLibrary('dart:async',