Bug 1151136 - Always initialize the aSeqno result from TabParent::RecvNotifyIMEFocus. r=masayuki

--HG--
extra : transplant_source : %7B%ECS%BB%BC%E0%EEI%8B%09%40%DFXe%B7E%20%CDv%5C

dom/ipc/TabParent.cpp

@@ -1579,13 +1579,14 @@ TabParent::RecvNotifyIMEFocus(const bool& aFocus,
                               nsIMEUpdatePreference* aPreference,
                               uint32_t* aSeqno)
 {
+  *aSeqno = mIMESeqno;
+
   nsCOMPtr<nsIWidget> widget = GetWidget();
   if (!widget) {
     *aPreference = nsIMEUpdatePreference();
     return true;
   }
 
-  *aSeqno = mIMESeqno;
   mIMETabParent = aFocus ? this : nullptr;
   mIMESelectionAnchor = 0;
   mIMESelectionFocus = 0;