Make unresolved access to top-level member a dynamic error.

lib/compiler/implementation/resolution/members.dart

Index: lib/compiler/implementation/resolution/members.dart
diff --git a/lib/compiler/implementation/resolution/members.dart b/lib/compiler/implementation/resolution/members.dart
index a6577afc5f3b0f359739cd5e11fc8b6205c58640..32f9bfbd4465ac9b2483e71ab16977c426e0c3dc 100644
--- a/lib/compiler/implementation/resolution/members.dart
+++ b/lib/compiler/implementation/resolution/members.dart
@@ -1557,7 +1557,9 @@ class ResolverVisitor extends CommonResolverVisitor<Element> {
       PrefixElement prefix = resolvedReceiver;
       target = prefix.lookupLocalMember(name);
       if (target == null) {
-        error(node, MessageKind.NO_SUCH_LIBRARY_MEMBER, [prefix.name, name]);
+        return warnAndCreateErroneousElement(
+            node, name, MessageKind.NO_SUCH_LIBRARY_MEMBER,
+            [prefix.name, name]);
       }
     }
     return target;