Undo making Flex,Row,Column const (#119669)

packages/flutter/lib/src/material/button_bar.dart

@@ -233,7 +233,7 @@ class ButtonBar extends StatelessWidget {
 class _ButtonBarRow extends Flex {
   /// Creates a button bar that attempts to display in a row, but displays in
   /// a column if there is insufficient horizontal space.
-  const _ButtonBarRow({
+  _ButtonBarRow({
     required super.children,
     super.mainAxisSize,
     super.mainAxisAlignment,

packages/flutter/lib/src/material/tabs.dart

@@ -275,7 +275,7 @@ class _TabLabelBarRenderer extends RenderFlex {
 // upon layout. The tab widths are only used at paint time (see _IndicatorPainter)
 // or in response to input.
 class _TabLabelBar extends Flex {
-  const _TabLabelBar({
+  _TabLabelBar({
     super.children,
     required this.onPerformLayout,
   }) : super(

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

@@ -4445,7 +4445,9 @@ class Flex extends MultiChildRenderObjectWidget {
   /// to be necessary to decide which direction to lay the children in or to
   /// disambiguate `start` or `end` values for the main or cross axis
   /// directions, the [textDirection] must not be null.
-  const Flex({
+  // TODO(goderbauer): Figure out whether this can be const.
+  // ignore: prefer_const_constructors_in_immutables
+  Flex({
     super.key,
     required this.direction,
     this.mainAxisAlignment = MainAxisAlignment.start,
@@ -4812,7 +4814,7 @@ class Row extends Flex {
   /// unless the row has no children or only one child) or to disambiguate
   /// `start` or `end` values for the [mainAxisAlignment], the [textDirection]
   /// must not be null.
-  const Row({
+  Row({
     super.key,
     super.mainAxisAlignment,
     super.mainAxisSize,
@@ -5005,7 +5007,7 @@ class Column extends Flex {
   /// any. If there is no ambient directionality, and a text direction is going
   /// to be necessary to disambiguate `start` or `end` values for the
   /// [crossAxisAlignment], the [textDirection] must not be null.
-  const Column({
+  Column({
     super.key,
     super.mainAxisAlignment,
     super.mainAxisSize,