Avoid excessive logging related to response handling locks (#11702)

Change-Id: I0e50663a2500c56a042d20c80909aacfc707a5dd

client/src/com/vaadin/client/ApplicationConnection.java

@@ -3287,6 +3287,14 @@ public class ApplicationConnection {
     Timer forceHandleMessage = new Timer() {
         @Override
         public void run() {
+            if (responseHandlingLocks.isEmpty()) {
+                /*
+                 * Timer fired but there's nothing to clear. This can happen
+                 * with IE8 as Timer.cancel is not always effective (see GWT
+                 * issue 8101).
+                 */
+                return;
+            }
             VConsole.log("WARNING: reponse handling was never resumed, forcibly removing locks...");
             responseHandlingLocks.clear();
             handlePendingMessages();
@@ -3311,9 +3319,13 @@ public class ApplicationConnection {
     public void resumeResponseHandling(Object lock) {
         responseHandlingLocks.remove(lock);
         if (responseHandlingLocks.isEmpty()) {
-            VConsole.log("No more response handling locks, handling pending requests.");
+            // Cancel timer that breaks the lock
             forceHandleMessage.cancel();
-            handlePendingMessages();
+
+            if (!pendingUIDLMessages.isEmpty()) {
+                VConsole.log("No more response handling locks, handling pending requests.");
+                handlePendingMessages();
+            }
         }
     }