Use entities in some full_emitter sublibraries

pkg/compiler/lib/src/common/backend_api.dart

Index: pkg/compiler/lib/src/common/backend_api.dart
diff --git a/pkg/compiler/lib/src/common/backend_api.dart b/pkg/compiler/lib/src/common/backend_api.dart
index a33f1fdffbf93b0ef962ac08d89de2ee9d3d1393..73e22cd4400660c604609e41221c05467268eefc 100644
--- a/pkg/compiler/lib/src/common/backend_api.dart
+++ b/pkg/compiler/lib/src/common/backend_api.dart
@@ -262,6 +262,10 @@ abstract class Backend extends Target {
   /// Returns true if this element needs reflection information at runtime.
   bool isAccessibleByReflection(Element element) => true;
 
+  /// Returns true if this member element needs reflection information at
+  /// runtime.
+  bool isMemberAccessibleByReflection(MemberElement element) => true;
+
   /// Returns true if this element is covered by a mirrorsUsed annotation.
   ///
   /// Note that it might still be ok to tree shake the element away if no