fix #29504, dcall on object member when a temporary was involved.

tests/language_strong/dynamic_invoke_test.dart

+// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+// Dart test program for testing dynamic calls.
+
+import "package:expect/expect.dart";
+
+// Make this something that DDC considers side effecting.
+dynamic get d => "hello";
+
+regress29504() {
+  // These forms were being incorrectly generated as dynamic invokes, which is
+  // not supposed to be done for the Object members that are always present on
+  // all Dart types, including `null`.
+  //
+  // See https://github.com/dart-lang/sdk/issues/29504
+  //
+  // What we're testing here is that none of these generate dynamic invokes,
+  // because that will throw a NoSuchMethod error if it happens.
+  Expect.equals(d.runtimeType, String);
+  Expect.equals(d?.runtimeType, String);
+  Expect.equals(d..runtimeType, "hello");
+
+  Expect.equals(d.hashCode, "hello".hashCode);
+  Expect.equals(d?.hashCode, "hello".hashCode);
+  Expect.equals(d..hashCode, "hello");
+
+  Expect.equals(d.toString(), "hello");
+  Expect.equals(d?.toString(), "hello");
+  Expect.equals(d..toString(), "hello");
+}
+
+main() {
+  regress29504();
+}