Add destroyed check

 Bug: 6350066

Change-Id: Icf077bcf9678a036a669124c27e56e191a935960

Author: jreck

core/java/android/webkit/WebViewCore.java

@@ -1772,6 +1772,9 @@ public Looper getWebKitLooper() {
 
         @Override
         public boolean dispatchWebKitEvent(MotionEvent event, int eventType, int flags) {
+            if (mNativeClass == 0) {
+                return false;
+            }
             switch (eventType) {
                 case WebViewInputDispatcher.EVENT_TYPE_CLICK:
                     return nativeMouseClick(mNativeClass);