Compute the paragraph drawing frame at mount time, not in layoutSubviews

`RCTParagraphComponentView` derives the text view's frame and drawing frame
in `layoutSubviews`, requested with `setNeedsLayout` from `updateState` and
`updateLayoutMetrics`. When a mount runs inside Core Animation's display
phase — which is where `AppleEventBeat` processes a synchronous event
requested during layout — this transaction's layout pass has already
happened, so the text view displays with the new attributed string but the
previous drawing frame: the text is cut off at the old width. The queued
`layoutSubviews` then updates the drawing frame in the next transaction,
but that property does not invalidate the display, so the clipped drawing
stays until something else redraws the view.

Compute the frames in `finalizeUpdates:` instead. The mounting manager calls
it once per view after all of a mutation's `update*` calls, so it coalesces
state and layout-metrics changes the same way the layout pass did, without
depending on a layout pass that may already be over. One computation per
mount, as before, minus the layout pass.

Author: janicduplessis

packages/react-native/React/Fabric/Mounting/ComponentViews/Text/RCTParagraphComponentView.mm

@@ -137,7 +137,6 @@ - (void)updateState:(const State::Shared &)state oldState:(const State::Shared &
 {
   _textView.state = std::static_pointer_cast<const ParagraphShadowNode::ConcreteState>(state);
   [_textView setNeedsDisplay];
-  [self setNeedsLayout];
 
   // If the attributed string has changed, we need to notify the accessibility system that something changed,
   // otherwise it may hold on to stale values (this happens most often when an element is updated async)
@@ -158,9 +157,18 @@ - (void)updateLayoutMetrics:(const LayoutMetrics &)layoutMetrics
   // re-applying individual sub-values which weren't changed.
   [super updateLayoutMetrics:layoutMetrics oldLayoutMetrics:_layoutMetrics];
   _textView.layoutMetrics = _layoutMetrics;
-  _textLayoutFrame = RCTCGRectFromRect(_layoutMetrics.getContentFrame());
   [_textView setNeedsDisplay];
-  [self setNeedsLayout];
+}
+
+- (void)finalizeUpdates:(RNComponentViewUpdateMask)updateMask
+{
+  [super finalizeUpdates:updateMask];
+  // Computed here rather than in `layoutSubviews`: a mount can run inside Core
+  // Animation's display phase, after this transaction's layout pass, and the
+  // text view would then draw with the previous frame.
+  if (updateMask & (RNComponentViewUpdateMaskState | RNComponentViewUpdateMaskLayoutMetrics)) {
+    [self _updateTextViewFrame];
+  }
 }
 
 - (void)prepareForRecycle
@@ -170,10 +178,8 @@ - (void)prepareForRecycle
   _accessibilityProvider = nil;
 }
 
-- (void)layoutSubviews
+- (void)_updateTextViewFrame
 {
-  [super layoutSubviews];
-
   CGRect textViewFrame = self.bounds;
   CGRect drawingFrame = RCTCGRectFromRect(_layoutMetrics.getContentFrame());