remove _AbortingSemanticsFragment (#88067)

packages/flutter/lib/src/rendering/object.dart

@@ -2754,25 +2754,11 @@ abstract class RenderObject extends AbstractNode with DiagnosticableTreeMixin im
     final Set<_InterestingSemanticsFragment> toBeMarkedExplicit = <_InterestingSemanticsFragment>{};
     final bool childrenMergeIntoParent = mergeIntoParent || config.isMergingSemanticsOfDescendants;
 
-    // When set to true there's currently not enough information in this subtree
-    // to compute semantics. In this case the walk needs to be aborted and no
-    // SemanticsNodes in the subtree should be updated.
-    // This will be true for subtrees that are currently kept alive by a
-    // viewport but not laid out.
-    bool abortWalk = false;
-
     visitChildrenForSemantics((RenderObject renderChild) {
-      if (abortWalk || _needsLayout) {
-        abortWalk = true;
-        return;
-      }
+      assert(!_needsLayout);
       final _SemanticsFragment parentFragment = renderChild._getSemanticsForParent(
         mergeIntoParent: childrenMergeIntoParent,
       );
-      if (parentFragment.abortsWalk) {
-        abortWalk = true;
-        return;
-      }
       if (parentFragment.dropsSemanticsOfPreviousSiblings) {
         fragments.clear();
         toBeMarkedExplicit.clear();
@@ -2803,10 +2789,6 @@ abstract class RenderObject extends AbstractNode with DiagnosticableTreeMixin im
       }
     });
 
-    if (abortWalk) {
-      return _AbortingSemanticsFragment(owner: this);
-    }
-
     for (final _InterestingSemanticsFragment fragment in toBeMarkedExplicit)
       fragment.markAsExplicit();
 
@@ -3535,17 +3517,6 @@ abstract class _SemanticsFragment {
   /// Returns [_InterestingSemanticsFragment] describing the actual semantic
   /// information that this fragment wants to add to the parent.
   List<_InterestingSemanticsFragment> get interestingFragments;
-
-  /// Whether this fragment wants to abort the semantics walk because the
-  /// information in the tree are not sufficient to calculate semantics.
-  ///
-  /// This happens for subtrees that are currently kept alive by a viewport but
-  /// not laid out.
-  ///
-  /// See also:
-  ///
-  ///  * [_AbortingSemanticsFragment], which sets this to true.
-  bool get abortsWalk => false;
 }
 
 /// A container used when a [RenderObject] wants to add multiple independent
@@ -3859,39 +3830,6 @@ class _SwitchableSemanticsFragment extends _InterestingSemanticsFragment {
   bool get _needsGeometryUpdate => _ancestorChain.length > 1;
 }
 
-
-/// [_SemanticsFragment] used to indicate that the current information in this
-/// subtree is not sufficient to update semantics.
-///
-/// Anybody processing this [_SemanticsFragment] should abort the walk of the
-/// current subtree without updating any [SemanticsNode]s as there is no semantic
-/// information to compute. As a result, this fragment also doesn't carry any
-/// semantics information either.
-class _AbortingSemanticsFragment extends _InterestingSemanticsFragment {
-  _AbortingSemanticsFragment({required RenderObject owner}) : super(owner: owner, dropsSemanticsOfPreviousSiblings: false);
-
-  @override
-  bool get abortsWalk => true;
-
-  @override
-  SemanticsConfiguration? get config => null;
-
-  @override
-  void addAll(Iterable<_InterestingSemanticsFragment> fragments) {
-    assert(false);
-  }
-
-  @override
-  void compileChildren({ Rect? parentSemanticsClipRect, Rect? parentPaintClipRect, required double elevationAdjustment, required List<SemanticsNode> result }) {
-    result.add(owner._semantics!);
-  }
-
-  @override
-  void markAsExplicit() {
-    // Is never explicit.
-  }
-}
-
 /// Helper class that keeps track of the geometry of a [SemanticsNode].
 ///
 /// It is used to annotate a [SemanticsNode] with the current information for