将WebClient与Unity WebGL一起使用时无法识别URI前缀

Question

下面的这些代码将生成错误“无法识别URI前缀”，我已经检查了该网址，它是正确的网址格式，这是我关于上传功能的服务器网址。

string url = "http://[skip]";
WebClient wc = new WebClient();      
byte[] result = wc.UploadData(url,"PUT", data);

Chrome开发者控制台中的错误结果如下：

NotSupportedException: The URI prefix is not recognized.
  at System.Net.WebRequest.Create (System.Uri requestUri, System.Boolean useUriBase) [0x00000] in <00000000000000000000000000000000>:0 
Rethrow as WebException: An exception occurred during a WebClient request.
  at System.Net.WebClient.UploadDataInternal (System.Uri address, System.String method, System.Byte[] data, System.Net.WebRequest& request) [0x00000] in <00000000000000000000000000000000>:0 

(Filename: currently not available on il2cpp Line: -1)

warning: 2 FS.syncfs operations in flight at once, probably just doing extra work

统一版本：2018.1.0b13

构建平台：WebGL

API兼容性级别：.Net 4.x

脚本运行时版本：稳定（.Net 4.x等效）