Bug 1346019 - Guard against null GeckoApp in GeckoUpdateReceiver; r=me

Don't dispatch the "Update:CheckResult" event if we don't have an active
GeckoApp. r=me for trivial patch.

mobile/android/base/java/org/mozilla/gecko/GeckoUpdateReceiver.java

@@ -17,6 +17,9 @@ public class GeckoUpdateReceiver extends BroadcastReceiver
     @Override
     public void onReceive(Context context, Intent intent) {
         if (UpdateServiceHelper.ACTION_CHECK_UPDATE_RESULT.equals(intent.getAction())) {
+            if (GeckoAppShell.getGeckoInterface() == null) {
+                return;
+            }
             final GeckoBundle data = new GeckoBundle(1);
             data.putString("result", intent.getStringExtra("result"));
             GeckoApp.getEventDispatcher().dispatch("Update:CheckResult", data);