[Layout Transition] Avoid calling didComplete method if pending layou…

…t transition is nil (#490)

* Avoid calling didComplete method if pending layout transition is nil

* Update CHANGELOG

CHANGELOG.md

@@ -11,6 +11,7 @@
 - Fix an issue that causes infinite layout loop in ASDisplayNode after [#428](https://github.com/TextureGroup/Texture/pull/428) [Huy Nguyen](https://github.com/nguyenhuy) [#455](https://github.com/TextureGroup/Texture/pull/455) 
 - Fix an issue in layout transition that causes it to unexpectedly use the old layout [Huy Nguyen](https://github.com/nguyenhuy) [#464](https://github.com/TextureGroup/Texture/pull/464)
 - Add -[ASDisplayNode detailedLayoutDescription] property to aid debugging. [Adlai Holler](https://github.com/Adlai-Holler) [#476](https://github.com/TextureGroup/Texture/pull/476)
+- Fix an issue that causes calculatedLayoutDidChange being called needlessly. [Huy Nguyen](https://github.com/nguyenhuy) [#490](https://github.com/TextureGroup/Texture/pull/490)
 
 ##2.3.5
 - Fix an issue where inserting/deleting sections could lead to inconsistent supplementary element behavior. [Adlai Holler](https://github.com/Adlai-Holler)

Source/ASDisplayNode+Layout.mm

@@ -850,8 +850,8 @@ - (void)_completePendingLayoutTransition
   if (pendingLayoutTransition != nil) {
     [self _setCalculatedDisplayNodeLayout:pendingLayoutTransition.pendingLayout];
     [self _completeLayoutTransition:pendingLayoutTransition];
+    [self _pendingLayoutTransitionDidComplete];
   }
-  [self _pendingLayoutTransitionDidComplete];
 }
 
 /**