Prefix bool variable with "should".
This is to address a comment in a CL landed earlier.

BUG=

Review-Url: https://codereview.webrtc.org/2137223002
Cr-Commit-Position: refs/heads/master@{#13435}
diff --git a/webrtc/sdk/objc/Framework/UnitTests/RTCConfigurationTest.mm b/webrtc/sdk/objc/Framework/UnitTests/RTCConfigurationTest.mm
index 51591f4..1fca960 100644
--- a/webrtc/sdk/objc/Framework/UnitTests/RTCConfigurationTest.mm
+++ b/webrtc/sdk/objc/Framework/UnitTests/RTCConfigurationTest.mm
@@ -44,7 +44,7 @@
   config.iceBackupCandidatePairPingInterval = interval;
   config.continualGatheringPolicy =
       RTCContinualGatheringPolicyGatherContinually;
-  config.pruneTurnPorts = true;
+  config.shouldPruneTurnPorts = YES;
 
   std::unique_ptr<webrtc::PeerConnectionInterface::RTCConfiguration>
       nativeConfig([config createNativeConfiguration]);