Fabric: Fixed ScrollView layout issue

Summary: We should not use `self.contentView` accessor to insert container views (views that might be used as a container for nested views) into component view otherwise it causes double applying of padding values.

Reviewed By: mdvacca

Differential Revision: D15862075

fbshipit-source-id: aad834aeca06f66b19c2f7bbaa0b58f937e66994

React/Fabric/Mounting/ComponentViews/ScrollView/RCTScrollViewComponentView.mm

@@ -46,8 +46,9 @@ using namespace facebook::react;
     _props = defaultProps;
 
     _scrollView = [[RCTEnhancedScrollView alloc] initWithFrame:self.bounds];
+    _scrollView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
     _scrollView.delaysContentTouches = NO;
-    self.contentView = _scrollView;
+    [self addSubview:_scrollView];
 
     _containerView = [[UIView alloc] initWithFrame:CGRectZero];
     [_scrollView addSubview:_containerView];