Fixes ScrollView centerContent not work in some cases (#24817)

Summary:
The bug description can see #24688, we add `contentView` size check before center the content, because in some cases, the contentView's size not yet be calculated, in those cases, we don't adjust the `contentOffset`.

cc. cpojer .

[iOS] [Fixed] - Fixes ScrollView centerContent not work in some cases
Pull Request resolved: #24817

Differential Revision: D15322502

Pulled By: sahrens

fbshipit-source-id: e2081f13e9f2e8597a379a9db1607451ea496909

React/Views/ScrollView/RCTScrollView.m

@@ -298,7 +298,7 @@ - (BOOL)touchesShouldCancelInContentView:(__unused UIView *)view
 - (void)setContentOffset:(CGPoint)contentOffset
 {
   UIView *contentView = [self contentView];
-  if (contentView && _centerContent) {
+  if (contentView && _centerContent && !CGSizeEqualToSize(contentView.frame.size, CGSizeZero)) {
     CGSize subviewSize = contentView.frame.size;
     CGSize scrollViewSize = self.bounds.size;
     if (subviewSize.width <= scrollViewSize.width) {