[refactor] improve link add page lock order

Author: zombieFox

src/js/link.js

@@ -1361,8 +1361,8 @@ var link = (function(){
 pagelock.unlock();
 }
 });
-stagedLink.position.destination.item=helper.e(".link-form-position").selectedIndex;
 pagelock.lock();
+stagedLink.position.destination.item=helper.e(".link-form-position").selectedIndex;
 },
 close: function(){
 mod.add.item.close();
@@ -1409,8 +1409,8 @@ var link = (function(){
 pagelock.unlock();
 }
 });
-stagedGroup.position.destination=helper.e(".group-form-position").selectedIndex;
 pagelock.lock();
+stagedGroup.position.destination=helper.e(".group-form-position").selectedIndex;
 },
 close: function(){
 mod.add.group.close();