Fix custom physics application in TabBarView (#58715)

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

@@ -1179,7 +1179,7 @@ class TabBarView extends StatefulWidget {
   _TabBarViewState createState() => _TabBarViewState();
 }
 
-final PageScrollPhysics _kTabBarViewPhysics = const PageScrollPhysics().applyTo(const ClampingScrollPhysics());
+const PageScrollPhysics _kTabBarViewPhysics = PageScrollPhysics();
 
 class _TabBarViewState extends State<TabBarView> {
   TabController _controller;
@@ -1349,7 +1349,9 @@ class _TabBarViewState extends State<TabBarView> {
       child: PageView(
         dragStartBehavior: widget.dragStartBehavior,
         controller: _pageController,
-        physics: widget.physics == null ? _kTabBarViewPhysics : _kTabBarViewPhysics.applyTo(widget.physics),
+        physics: widget.physics == null
+          ? _kTabBarViewPhysics.applyTo(const ClampingScrollPhysics())
+          : _kTabBarViewPhysics.applyTo(widget.physics),
         children: _childrenWithKey,
       ),
     );

packages/flutter/test/material/tabs_test.dart

@@ -2580,4 +2580,22 @@ void main() {
     await tester.pumpAndSettle();
     pageController.removeListener(pageControllerListener);
   });
+
+  testWidgets('Setting BouncingScrollPhysics on TabBarView does not include ClampingScrollPhysics', (WidgetTester tester) async {
+    // Regression test for https://github.com/flutter/flutter/issues/57708
+    await tester.pumpWidget(MaterialApp(
+      home: DefaultTabController(
+        length: 10,
+        child: Scaffold(
+          body: TabBarView(
+            physics: const BouncingScrollPhysics(),
+            children: List<Widget>.generate(10, (int i) => Center(child: Text('index $i'))),
+          ),
+        ),
+      )
+    ));
+
+    final PageView pageView = tester.widget<PageView>(find.byType(PageView));
+    expect(pageView.physics.toString().contains('ClampingScrollPhysics'), isFalse);
+  });
 }