[Modify] Polish it

websocket-sharp/WebSocket.cs

@@ -1711,12 +1711,15 @@ namespace WebSocketSharp
         return;
 
       var buff = new StringBuilder (80);
-
       var comp = false;
-      foreach (var e in value.SplitHeaderValue (',')) {
-        var ext = e.Trim ();
-        if (!comp && ext.IsCompressionExtension (CompressionMethod.Deflate)) {
+
+      foreach (var val in value.SplitHeaderValue (',')) {
+        var ext = val.Trim ();
+
+        if (!comp) {
+          if (ext.IsCompressionExtension (CompressionMethod.Deflate)) {
             _compression = CompressionMethod.Deflate;
+
             buff.AppendFormat (
               "{0}, ",
               _compression.ToExtensionString (
@@ -1727,13 +1730,15 @@ namespace WebSocketSharp
             comp = true;
           }
         }
+      }
 
       var len = buff.Length;
-      if (len > 2) {
+      if (len <= 2)
+        return;
+
       buff.Length = len - 2;
       _extensions = buff.ToString ();
     }
-    }
 
     // As client
     private void processSecWebSocketExtensionsServerHeader (string value)