Replace Where+FirstOrDefault with FirstOrDefault in SocketClient (#636)

* Replace Where.FirstOrDefault with FirstOrDefault

* Replace Where+FirstOrDefault in ClientHelper

src/Discord.Net.Rest/ClientHelper.cs

@@ -150,7 +150,7 @@ namespace Discord.Rest
             string id, RequestOptions options)
         {
             var models = await client.ApiClient.GetVoiceRegionsAsync(options).ConfigureAwait(false);
-            return models.Select(x => RestVoiceRegion.Create(client, x)).Where(x => x.Id == id).FirstOrDefault();
+            return models.Select(x => RestVoiceRegion.Create(client, x)).FirstOrDefault(x => x.Id == id);
         }
     }
 }

src/Discord.Net.WebSocket/DiscordSocketClient.cs

@@ -267,7 +267,7 @@ namespace Discord.WebSocket
         /// <inheritdoc />
         public SocketUser GetUser(string username, string discriminator)
         {
-            return State.Users.Where(x => x.Discriminator == discriminator && x.Username == username).FirstOrDefault();
+            return State.Users.FirstOrDefault(x => x.Discriminator == discriminator && x.Username == username);
         }
         internal SocketGlobalUser GetOrCreateUser(ClientState state, Discord.API.User model)
         {