Handle super accesses loaded from .dill

pkg/compiler/lib/src/ssa/kernel_ast_adapter.dart

Index: pkg/compiler/lib/src/ssa/kernel_ast_adapter.dart
diff --git a/pkg/compiler/lib/src/ssa/kernel_ast_adapter.dart b/pkg/compiler/lib/src/ssa/kernel_ast_adapter.dart
index 5ea20189a3df169c8faae1bb8200138f9c3c16bd..0ff8608bf617171d6cc20719247e30eaea068c45 100644
--- a/pkg/compiler/lib/src/ssa/kernel_ast_adapter.dart
+++ b/pkg/compiler/lib/src/ssa/kernel_ast_adapter.dart
@@ -182,9 +182,17 @@ class KernelAstAdapter extends KernelToElementMapMixin {
   @override
   ConstructorEntity getSuperConstructor(
       ir.Constructor constructor, ir.Member target) {
+    assert(target != null);
     return getConstructor(target);
   }
 
+  @override
+  MemberEntity getSuperMember(ir.Member context, ir.Name name, ir.Member target,
+      {bool setter: false}) {
+    assert(target != null);
+    return getMember(target);
+  }
+
   MemberElement getMember(ir.Member node) => getElement(node).declaration;
 
   MethodElement getMethod(ir.Procedure node) => getElement(node).declaration;