Add a test for negated type with `all` option

Related feedback:
- https://github.com/uBlockOrigin/uAssets/issues/7639#issuecomment-933525018

platform/npm/tests/snfe.js

@@ -287,6 +287,18 @@ describe('SNFE', () => {
                     });
                     assert(engine.isBlockImportant());
                 });
+
+                it('should block all except stylesheets', async () => {
+                    await engine.useLists([
+                        { name: 'test', raw: '||example.com^$~stylesheet,all' },
+                    ]);
+                    const r = engine.matchRequest({
+                        originURL: 'https://www.example.com/',
+                        type: 'stylesheet',
+                        url: 'https://www.example.com/',
+                    });
+                    assert.strictEqual(r, 0);
+                });
             });
         });
     }