Remove newline (flutter#121090)

* remove newline

* update crswap

* add const constructor

* update const

Author: Eilidh Southren

dev/tools/gen_defaults/lib/checkbox_template.dart

@@ -112,8 +112,8 @@ class _${blockName}DefaultsM3 extends CheckboxThemeData {
   VisualDensity get visualDensity => _theme.visualDensity;
 
   @override
-  OutlinedBorder get shape => RoundedRectangleBorder(
-    borderRadius: BorderRadius.circular(${tokens['md.comp.checkbox.unselected.outline.width']}),
+  OutlinedBorder get shape => const RoundedRectangleBorder(
+    borderRadius: BorderRadius.all(Radius.circular(${tokens['md.comp.checkbox.unselected.outline.width']})),
   );
 }
 ''';

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

@@ -874,8 +874,8 @@ class _CheckboxDefaultsM3 extends CheckboxThemeData {
   VisualDensity get visualDensity => _theme.visualDensity;
 
   @override
-  OutlinedBorder get shape => RoundedRectangleBorder(
-    borderRadius: BorderRadius.circular(2.0),
+  OutlinedBorder get shape => const RoundedRectangleBorder(
+    borderRadius: BorderRadius.all(Radius.circular(2.0)),
   );
 }
 

packages/flutter/test/material/checkbox_test.dart

@@ -1748,7 +1748,6 @@ void main() {
               return Checkbox(
                 value: false,
                 onChanged: (bool? newValue) {},
-
               );
             }),
           ),