code readability: fix awkward variable shadowing (#23886)

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

@@ -2414,17 +2414,17 @@ abstract class RenderObject extends AbstractNode with DiagnosticableTreeMixin im
     final bool childrenMergeIntoParent = mergeIntoParent || config.isMergingSemanticsOfDescendants;
 
     visitChildrenForSemantics((RenderObject renderChild) {
-      final _SemanticsFragment fragment = renderChild._getSemanticsForParent(
+      final _SemanticsFragment parentFragment = renderChild._getSemanticsForParent(
         mergeIntoParent: childrenMergeIntoParent,
       );
-      if (fragment.dropsSemanticsOfPreviousSiblings) {
+      if (parentFragment.dropsSemanticsOfPreviousSiblings) {
         fragments.clear();
         toBeMarkedExplicit.clear();
         if (!config.isSemanticBoundary)
           dropSemanticsOfPreviousSiblings = true;
       }
       // Figure out which child fragments are to be made explicit.
-      for (_InterestingSemanticsFragment fragment in fragment.interestingFragments) {
+      for (_InterestingSemanticsFragment fragment in parentFragment.interestingFragments) {
         fragments.add(fragment);
         fragment.addAncestor(this);
         fragment.addTags(config.tagsForChildren);

packages/flutter/test/widgets/semantics_tester.dart

@@ -296,10 +296,10 @@ class TestSemantics {
       return true;
     bool result = true;
     final Iterator<TestSemantics> it = children.iterator;
-    for (final SemanticsNode node in node.debugListChildrenInOrder(childOrder)) {
+    for (final SemanticsNode child in node.debugListChildrenInOrder(childOrder)) {
       it.moveNext();
       final bool childMatches = it.current._matches(
-        node,
+        child,
         matchState,
         ignoreRect: ignoreRect,
         ignoreTransform: ignoreTransform,