synchronized clearing of CaretTextOverlayListener timer to prevent npe #642

Author: Haehnchen

src/fr/adrienbrault/idea/symfony2plugin/codeInsight/caret/overlay/CaretTextOverlayListener.java

@@ -85,7 +85,7 @@ private void removeOverlays(@NotNull Editor editor) {
         }
     }
 
-    private void clear() {
+    synchronized private void clear() {
         if(timer == null) {
             return;
         }