Make sure that a BottomSheet doesn't crash in 0x0 environment (flutter#172229)

This is my attempt to handle flutter#6537 for the BottomSheet UI control.

---------

Co-authored-by: Tong Mu <dkwingsmt@users.noreply.github.com>
Co-authored-by: Victor Sanni <victorsanniay@gmail.com>

Author: 3 people

packages/flutter/test/material/bottom_sheet_test.dart

@@ -2889,6 +2889,24 @@ void main() {
     expect(FocusScope.of(tester.element(find.text('BottomSheet'))).hasFocus, false);
     expect(focusNode.hasFocus, true);
   });
+
+  testWidgets('BottomSheet does not crash at zero area', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Scaffold(
+          body: Center(
+            child: SizedBox.shrink(
+              child: BottomSheet(
+                onClosing: () {},
+                builder: (BuildContext context) => const Text('X'),
+              ),
+            ),
+          ),
+        ),
+      ),
+    );
+    expect(tester.getSize(find.byType(BottomSheet)), Size.zero);
+  });
 }
 
 class _TestPage extends StatelessWidget {