Clean up NestedScrollView TODOs (#84594)

packages/flutter/lib/src/widgets/nested_scroll_view.dart

@@ -341,7 +341,7 @@ typedef NestedScrollViewHeaderSliversBuilder = List<Widget> Function(BuildContex
 ///
 /// ### Stretching [SliverAppBar]s
 ///
-// TODO(Piinks): Support stretching, https://github.com/flutter/flutter/issues/54059
+// See https://github.com/flutter/flutter/issues/54059
 /// Currently, [NestedScrollView] does not support stretching the outer
 /// scrollable, e.g. when using [SliverAppBar.stretch].
 ///
@@ -1250,10 +1250,6 @@ class _NestedScrollCoordinator implements ScrollActivityDelegate, ScrollHoldCont
           outerDelta -= _outerPosition!.applyClampedDragUpdate(outerDelta);
 
         // Now deal with any overscroll
-        // TODO(Piinks): Configure which scrollable receives overscroll to
-        // support stretching app bars. createOuterBallisticScrollActivity will
-        // need to be updated as it currently assumes the outer position will
-        // never overscroll, https://github.com/flutter/flutter/issues/54059
         for (int i = 0; i < innerPositions.length; ++i) {
           final double remainingDelta = overscrolls[i] - outerDelta;
           if (remainingDelta > 0.0)