fix(fabric): remove autoresizingMask on ScrollView documentView to fix Text overflow

On macOS, the _containerView (NSScrollView's documentView) had
autoresizingMask set to FlexibleWidth | FlexibleHeight. This conflicts
with React's explicit frame management: when AppKit's NSClipView resizes
(e.g., during initial tile after mounting), autoresizing adds the clip
view's size delta to the container's dimensions, inflating it well beyond
the correct content size and producing massive horizontal and vertical
overflow on first render. Resizing the window triggers a React re-layout
that overwrites the corrupted frame, which is why the issue self-corrects.

The fix removes the autoresizingMask so React's layout system (via
updateState:) is the sole manager of the documentView's frame. This is
consistent with the Paper architecture, which never set autoresizingMask
on the documentView.

Fixes #2857

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Saadnajmi

packages/react-native/React/Fabric/Mounting/ComponentViews/ScrollView/RCTScrollViewComponentView.mm

@@ -157,7 +157,12 @@ - (instancetype)initWithFrame:(CGRect)frame
 #if !TARGET_OS_OSX // [macOS]
     [_scrollView addSubview:_containerView];
 #else // [macOS
-    _containerView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
+    // Do not set autoresizingMask on _containerView. On macOS, the _containerView serves as the
+    // NSScrollView's documentView, and its frame directly determines the scrollable content area.
+    // React's layout system (via updateState:) explicitly manages the _containerView's frame to
+    // match the content bounding rect. Setting autoresizingMask causes AppKit's autoresizing to
+    // resize the _containerView whenever the NSClipView resizes (e.g., on initial tile or window
+    // resize), corrupting the frame that React set and producing massive overflow on first render.
     [_scrollView setDocumentView:_containerView];
 #endif // macOS]