Fix #6771 if a session times out and the browser was never started, it should still be cleaned up on the hub side.

BeforeRelease should then be a no-op and not throw.

Author: freynaud

java/server/src/org/openqa/grid/selenium/proxy/DefaultRemoteProxy.java

@@ -78,10 +78,9 @@ public DefaultRemoteProxy(RegistrationRequest request, Registry registry) {
   }
 
   public void beforeRelease(TestSession session) {
-    // release the resources remotely.
+    // release the resources remotely if the remote started a browser.
     if (session.getExternalKey() == null) {
-      throw new IllegalStateException(
-          "cannot release the resources, they haven't been reserved properly.");
+      return;
     }
     boolean ok = session.sendDeleteSessionRequest();
     if (!ok) {