Android shouldn't dispatch onLayout if frame didn't change

Summary:
Fixes [#7202 Android Redundant onLayout event](https://github.com/facebook/react-native/issues/7202)
Closes https://github.com/facebook/react-native/pull/7250

Differential Revision: D4104066

Pulled By: mkonicek

fbshipit-source-id: 383efdb4b4881aa7d7e508d61c9c01165bcf7bb6

ReactAndroid/src/main/java/com/facebook/react/uimanager/UIImplementation.java

@@ -789,14 +789,16 @@ public class UIImplementation {
 
     int tag = cssNode.getReactTag();
     if (!mShadowNodeRegistry.isRootNode(tag)) {
-      cssNode.dispatchUpdates(
+      boolean frameDidChange = cssNode.dispatchUpdates(
           absoluteX,
           absoluteY,
           mOperationsQueue,
           mNativeViewHierarchyOptimizer);
 
-      // notify JS about layout event if requested
-      if (cssNode.shouldNotifyOnLayout()) {
+      // Notify JS about layout event if requested
+      // and if the position or dimensions actually changed
+      // (consistent with iOS).
+      if (frameDidChange && cssNode.shouldNotifyOnLayout()) {
         mEventDispatcher.dispatchEvent(
             OnLayoutEvent.obtain(
                 tag,