[Refactor] no-unused-state: avoid a loop

lib/rules/no-unused-state.js

@@ -139,19 +139,15 @@ module.exports = {
     // Takes an ObjectExpression node and adds all named Property nodes to the
     // current set of state fields.
     function addStateFields(node) {
-      for (const prop of node.properties) {
-        const key = prop.key;
-
-        if (
-          prop.type === 'Property'
-          && (key.type === 'Literal'
-          || (key.type === 'TemplateLiteral' && key.expressions.length === 0)
-          || (prop.computed === false && key.type === 'Identifier'))
+      node.properties.filter((prop) => (
+        prop.type === 'Property'
+          && (prop.key.type === 'Literal'
+          || (prop.key.type === 'TemplateLiteral' && prop.key.expressions.length === 0)
+          || (prop.computed === false && prop.key.type === 'Identifier'))
           && getName(prop.key) !== null
-        ) {
-          classInfo.stateFields.add(prop);
-        }
-      }
+      )).forEach((prop) => {
+        classInfo.stateFields.add(prop);
+      });
     }
 
     // Adds the name of the given node as a used state field if the node is an