[Fix] disallow extra properties in rule options

Author: andreww2012

src/rules/label-has-for.js

@@ -26,6 +26,7 @@ const schema = {
     },
     allowChildren: { type: 'boolean' },
   },
+  additionalProperties: false,
 };
 // Breadth-first search, assuming that HTML for forms is shallow.
 function validateNesting(node) {

src/util/schemas.js

@@ -30,4 +30,5 @@ export const generateObjSchema = (properties = {}, required = undefined) => ({
   type: 'object',
   properties,
   required,
+  additionalProperties: false,
 });