Improve instruction scheduling when calling the store buffer stub.

runtime/vm/assembler_x64.cc

Index: runtime/vm/assembler_x64.cc
diff --git a/runtime/vm/assembler_x64.cc b/runtime/vm/assembler_x64.cc
index 7b2f39107c29fae43a29f253999449fa64b0fdb4..da4021a02e37d1b3bb1ba953afc69fe733d2f6ea 100644
--- a/runtime/vm/assembler_x64.cc
+++ b/runtime/vm/assembler_x64.cc
@@ -2953,8 +2953,8 @@ void Assembler::StoreIntoObject(Register object,
     movq(RDX, object);
   }
   pushq(CODE_REG);
-  movq(CODE_REG, Address(THR, Thread::update_store_buffer_code_offset()));
   movq(TMP, Address(THR, Thread::update_store_buffer_entry_point_offset()));
+  movq(CODE_REG, Address(THR, Thread::update_store_buffer_code_offset()));
   call(TMP);
 
   popq(CODE_REG);