Fixups for master CI (#2118)

## Pre-launch Checklist

- [x] I read the [Flutter Style Guide] _recently_, and have followed its
advice.
- [x] I signed the [CLA].
- [x] I read the [Contributors Guide].
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-devrel
channel on [Discord].

<!-- Links -->
[Flutter Style Guide]:
https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo
[CLA]: https://cla.developers.google.com/
[Discord]: https://github.com/flutter/flutter/wiki/Chat
[Contributors Guide]:
https://github.com/flutter/samples/blob/main/CONTRIBUTING.md

experimental/linting_tool/lib/pages/saved_lints_page.dart

@@ -101,7 +101,7 @@ class _SavedLintsPageState extends State<SavedLintsPage> {
                               var saved = await profilesStore
                                   .exportProfileFile(profile);
 
-                              if (!mounted) return;
+                              if (!context.mounted) return;
 
                               if (!saved) {
                                 _showSnackBar(

experimental/linting_tool/lib/widgets/lint_expansion_tile.dart

@@ -140,7 +140,7 @@ class _LintExpansionTileState extends State<LintExpansionTile> {
                   return const _ProfileTypeDialog();
                 },
               );
-              if (!mounted) return;
+              if (!context.mounted) return;
               if (destinationProfileType == ProfileType.newProfile) {
                 await showDialog<String>(
                   context: context,
@@ -264,7 +264,7 @@ class _NewProfileDialogState extends State<NewProfileDialog> {
               );
               await Provider.of<ProfilesStore>(context, listen: false)
                   .addToNewProfile(newProfile);
-              if (!mounted) return;
+              if (!context.mounted) return;
               Navigator.pop(context);
             }
           },
@@ -304,7 +304,7 @@ class _ExistingProfileDialogState extends State<ExistingProfileDialog> {
             onTap: () async {
               await profilesStore.addToExistingProfile(
                   savedProfiles[index], widget.rule);
-              if (!mounted) return;
+              if (!context.mounted) return;
               Navigator.pop(context);
             },
           ),