Handle deferred access as pre-step in SemanticSendVisitor.

pkg/compiler/lib/src/inferrer/inferrer_visitor.dart

Index: pkg/compiler/lib/src/inferrer/inferrer_visitor.dart
diff --git a/pkg/compiler/lib/src/inferrer/inferrer_visitor.dart b/pkg/compiler/lib/src/inferrer/inferrer_visitor.dart
index e8af9783dccabcb236a7a7f8aa2d0c2765e0eff2..0e83908c7b5d5e2b8536cf51cc4807d0f2ef1cba 100644
--- a/pkg/compiler/lib/src/inferrer/inferrer_visitor.dart
+++ b/pkg/compiler/lib/src/inferrer/inferrer_visitor.dart
@@ -816,6 +816,11 @@ abstract class InferrerVisitor
     return types.dynamicType;
   }
 
+  @override
+  void visitDeferredAccess(Send node, PrefixElement prefix, _) {
+    // Deferred access does not affect inference.
+  }
+
   T handleTypeLiteralGet() {
     return types.typeType;
   }