fix windows after r18847

src/x64/stub-cache-x64.cc

Index: src/x64/stub-cache-x64.cc
diff --git a/src/x64/stub-cache-x64.cc b/src/x64/stub-cache-x64.cc
index fce9b92c94ad66ac74736ebef279e0d0f32e7183..a84eb1f63ba12f5cef3f2ee10c1a4cebab28a363 100644
--- a/src/x64/stub-cache-x64.cc
+++ b/src/x64/stub-cache-x64.cc
@@ -1252,7 +1252,12 @@ void LoadStubCompiler::GenerateLoadCallback(
 
   Address thunk_address = FUNCTION_ADDR(&InvokeAccessorGetterCallback);
 
-  Register api_function_address = rdx;
+  Register api_function_address = r8;
+  // It's okay if api_function_address == getter_arg
+  // but not accessor_info_arg or name_arg
+  ASSERT(!api_function_address.is(accessor_info_arg) &&
+         !api_function_address.is(name_arg));
+
   __ Move(api_function_address, getter_address, RelocInfo::EXTERNAL_REFERENCE);
 
   // The name handler is counted as an argument.