修复使用RawObject处理byte[]作为函数参数时，byte[]为null的问题，ps: 在lua侧调用FileStream.Read(byte[] buffer, int offset, int length)接口 (#917)

Author: hq2x

Assets/XLua/Src/ObjectCasters.cs

@@ -314,7 +314,12 @@ private static object getString(RealStatePtr L, int idx, object target)
 
         private object getBytes(RealStatePtr L, int idx, object target)
         {
-            return LuaAPI.lua_type(L, idx) == LuaTypes.LUA_TSTRING ? LuaAPI.lua_tobytes(L, idx) : translator.SafeGetCSObj(L, idx) as byte[];
+            if(LuaAPI.lua_type(L, idx) == LuaTypes.LUA_TSTRING)
+            {
+                return LuaAPI.lua_tobytes(L, idx);
+            }
+            object obj = translator.SafeGetCSObj(L, idx);
+            return (obj is RawObject) ? (obj as RawObject).Target : obj as byte[];
         }
 
         private object getIntptr(RealStatePtr L, int idx, object target)