[flutter roll] Revert "Fix floating SnackBar throws when FAB is on the top" (#131303)

Reverts flutter/flutter#129274

temporarily putting up a revert in case a fix is difficult
context: [b/293202068](http://b/293202068) youtube integration tests failed

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

@@ -1142,31 +1142,7 @@ class _ScaffoldLayout extends MultiChildLayoutDelegate {
       }
 
       final double snackBarYOffsetBase;
-      final bool showAboveFab = switch (currentFloatingActionButtonLocation) {
-        FloatingActionButtonLocation.startTop
-        || FloatingActionButtonLocation.centerTop
-        || FloatingActionButtonLocation.endTop
-        || FloatingActionButtonLocation.miniStartTop
-        || FloatingActionButtonLocation.miniCenterTop
-        || FloatingActionButtonLocation.miniEndTop => false,
-        FloatingActionButtonLocation.startDocked
-        || FloatingActionButtonLocation.startFloat
-        || FloatingActionButtonLocation.centerDocked
-        || FloatingActionButtonLocation.centerFloat
-        || FloatingActionButtonLocation.endContained
-        || FloatingActionButtonLocation.endDocked
-        || FloatingActionButtonLocation.endFloat
-        || FloatingActionButtonLocation.miniStartDocked
-        || FloatingActionButtonLocation.miniStartFloat
-        || FloatingActionButtonLocation.miniCenterDocked
-        || FloatingActionButtonLocation.miniCenterFloat
-        || FloatingActionButtonLocation.miniEndDocked
-        || FloatingActionButtonLocation.miniEndFloat => true,
-        FloatingActionButtonLocation() => throw FlutterError(
-          '$currentFloatingActionButtonLocation is an unknown FloatingActionButtonLocation value.'
-        ),
-      };
-      if (floatingActionButtonRect.size != Size.zero && isSnackBarFloating && showAboveFab) {
+      if (floatingActionButtonRect.size != Size.zero && isSnackBarFloating) {
         snackBarYOffsetBase = floatingActionButtonRect.top;
       } else {
         // SnackBarBehavior.fixed applies a SafeArea automatically.

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

@@ -12,22 +12,19 @@ import 'theme.dart';
 
 /// Defines where a [SnackBar] should appear within a [Scaffold] and how its
 /// location should be adjusted when the scaffold also includes a
-/// [FloatingActionButton], a [BottomNavigationBar], or a [NavigationBar].
+/// [FloatingActionButton] or a [BottomNavigationBar].
 enum SnackBarBehavior {
   /// Fixes the [SnackBar] at the bottom of the [Scaffold].
   ///
   /// The exception is that the [SnackBar] will be shown above a
-  /// [BottomNavigationBar] or a [NavigationBar]. Additionally, the [SnackBar]
-  /// will cause other non-fixed widgets inside [Scaffold] to be pushed above
-  /// (for example, the [FloatingActionButton]).
+  /// [BottomNavigationBar]. Additionally, the [SnackBar] will cause other
+  /// non-fixed widgets inside [Scaffold] to be pushed above (for example, the
+  /// [FloatingActionButton]).
   fixed,
 
   /// This behavior will cause [SnackBar] to be shown above other widgets in the
-  /// [Scaffold]. This includes being displayed above a [BottomNavigationBar] or
-  /// a [NavigationBar], and a [FloatingActionButton] when its location is on the
-  /// bottom. When the floating action button location is on the top, this behavior
-  /// will cause the [SnackBar] to be shown above other widgets in the [Scaffold]
-  /// except the floating action button.
+  /// [Scaffold]. This includes being displayed above a [BottomNavigationBar]
+  /// and a [FloatingActionButton].
   ///
   /// See <https://material.io/design/components/snackbars.html> for more details.
   floating,

packages/flutter/test/material/snack_bar_test.dart

@@ -2071,59 +2071,6 @@ void main() {
       },
     );
 
-    testWidgets(
-      '${SnackBarBehavior.floating} should not align SnackBar with the top of FloatingActionButton '
-      'when Scaffold has a FloatingActionButton and floatingActionButtonLocation is set to a top position',
-      (WidgetTester tester) async {
-        Future<void> pumpApp({required FloatingActionButtonLocation fabLocation}) async {
-          return tester.pumpWidget(MaterialApp(
-            home: Scaffold(
-              floatingActionButton: FloatingActionButton(
-                child: const Icon(Icons.send),
-                onPressed: () {},
-              ),
-              floatingActionButtonLocation: fabLocation,
-              body: Builder(
-                builder: (BuildContext context) {
-                  return GestureDetector(
-                    onTap: () {
-                      ScaffoldMessenger.of(context).showSnackBar(SnackBar(
-                        content: const Text('I am a snack bar.'),
-                        duration: const Duration(seconds: 2),
-                        action: SnackBarAction(label: 'ACTION', onPressed: () {}),
-                        behavior: SnackBarBehavior.floating,
-                      ));
-                    },
-                    child: const Text('X'),
-                  );
-                },
-              ),
-            ),
-          ));
-        }
-
-        const List<FloatingActionButtonLocation> topLocations = <FloatingActionButtonLocation>[
-          FloatingActionButtonLocation.startTop,
-          FloatingActionButtonLocation.centerTop,
-          FloatingActionButtonLocation.endTop,
-          FloatingActionButtonLocation.miniStartTop,
-          FloatingActionButtonLocation.miniCenterTop,
-          FloatingActionButtonLocation.miniEndTop,
-        ];
-
-        for (final FloatingActionButtonLocation location in topLocations) {
-          await pumpApp(fabLocation: location);
-
-          await tester.tap(find.text('X'));
-          await tester.pumpAndSettle(); // Have the SnackBar fully animate out.
-
-          final Offset snackBarBottomLeft = tester.getBottomLeft(find.byType(SnackBar));
-
-          expect(snackBarBottomLeft.dy, 600); // Device height is 600.
-        }
-      },
-    );
-
     testWidgets(
       '${SnackBarBehavior.fixed} should align SnackBar with the top of BottomNavigationBar '
       'when Scaffold has a BottomNavigationBar and FloatingActionButton',